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8 3/4 strength poll!!
Posted By: hemiluver
8 3/4 strength poll!! - 08/26/08 07:12 PM
Gents,
I asked a question earlier about the 8 3/4 rearend and its strength. I went on FAST to see what Tom Cannon runs, an 8 3/4-runs-11's or Ralph Barbagallo's 70 Bird runs low 11's at near 3800#'s with him in it.How much power are you guys hitting your 8 3/4's with? Are you supercharged,nitrous,etc,etc. Lets see some hard real numbers to make an informed decision.I know the Dana's better but much more$$$.I'm not running 8's either.High 11's low 12's @ 5800 ft.- Thanks guys,Gary
Posted By: ramrod
Re: 8 3/4 strength poll!! - 08/26/08 07:46 PM
I've put 500+ passes on mine. W2 smallblock, torqueflite, 3000lb A-body. Spool, aftermarket axles, 4.86 gear, green bearings, 14 inch wide slicks. 10.90 in the quarter. It's been absolutely maintenance free.
Posted By: goldmember
Re: 8 3/4 strength poll!! - 08/26/08 07:48 PM
If you don't already have the 8 3/4 a Dana isn't alot more expensive. Truck housings can still be found for under $100.00 add ends $85.00 and labor to have shortened$150.00. Good axles are the same price for either rear,spools or limited slips can be had for either. The 8 3/4 is a great rear for a street stip car,but as you get into the 10's or quicker the Dana has is the better choice. I recently sold an 8 3/4 complete with good axles that had never been broken in my 10 years and 1000's of passes,but sold it an built a Dana and had money left over.
back brace it and go
I will stay 8 3/4 myself just for quick gear changes
lets see that with a D60
Posted By: E-Ticket
Re: 8 3/4 strength poll!! - 08/26/08 08:54 PM
Put some 1:30 & better 60' times and a trans. brake up against an 8-3/4 housing and see how long it lasts! I have a useless back braced housing to prove it! If your not running a class that your looking to shave hundreths of a second off of, spend the $$$ and go Dana....your budget will thank you in the long run!
Posted By: hemiluver
Re: 8 3/4 strength poll!! - 08/26/08 09:01 PM
Ok thanks for some info,but as said what real #'s are we talking,give me ETs and weights. And to all you guys,YES WE KNOW D-60's are the strongest.But for a guys with an 8 3/4 what can we push the limits too-and have longevity.
Posted By: viperakron
Re: 8 3/4 strength poll!! - 08/26/08 09:11 PM
I used a slightly modified one in a 3200# Nostalgia SS car that ran 10.0s. Did some minor bracing and welded the tubes to the center section. A stock one bent the axle tubes forward
Posted By: E-Ticket
Re: 8 3/4 strength poll!! - 08/26/08 09:16 PM
Challenger, 3400#'s, trans. brake, ladder bars, 6:20's equals a bent braced 8-3/4 housing.....it now has a 4-link and a Dana!
If your running high 11's, low 12's and so on....you should be fine with an 8-3/4 but like "scratchnfotraction" said, back brace it & go... If your going to use an 8-3/4, I would definitely brace it. Ladder Bar cars are real hard on rear end housings more so than 4-link cars and if your just using super stock leaf springs & or Cal Tracs or something like that, a braced 8-3/4 should be fine.
One more thing....the shorter the housing, the stronger it is and less "likely" to bend.
Posted By: kenworth_goose
Re: 8 3/4 strength poll!! - 08/26/08 10:17 PM
I know someone that has a 69 superbee, hemi runs 8.90's with an 8 3/4 no back brace. It has never broke. Maybe you guys are getting it to hot welding the brace on?
Posted By: E-Ticket
Re: 8 3/4 strength poll!! - 08/26/08 10:38 PM
Sounds like he is lucky to keep it in the car and straight? Heat....could be but I know the SS/AA or now called SS/AH cars (due to re-classifying these cars because of the Bow Tie Whiners).......run that e.t. and quicker, could not keep 8-3/4's in their cars back in the day and some of those cars used to use 12 bolt Chevrolet rear ends because they were the lightest but bent also, a lot of them are using dana's even though they are heaviest and some are to this day, using braced 9" housings.
Posted By: JohnRR
Re: 8 3/4 strength poll!! - 08/27/08 12:34 AM
Quote:
Ok thanks for some info,but as said what real #'s are we talking,give me ETs and weights. And to all you guys,YES WE KNOW D-60's are the strongest.But for a guys with an 8 3/4 what can we push the limits too-and have longevity.
how about telling how YOU WILL USE THE CAR , what tires , 4 speed or automatic , dumping the clutch at 5000 rpm with slicks ???
Posted By: Neil
Re: 8 3/4 strength poll!! - 08/27/08 12:40 AM
F.A.S.T guys have skinny reproduction bias-ply tires and probably leave at relatively low rpm's because of that fact.
Posted By: JohnRR
Re: 8 3/4 strength poll!! - 08/27/08 12:42 AM
Quote:
F.A.S.T guys have skinny reproduction bias-ply tires and probably leave at relatively low rpm's because of that fact.
ding ding ding .... WINNER
Posted By: BigMoneyLewis
Re: 8 3/4 strength poll!! - 08/27/08 01:01 AM
The 68 Hurst Hemi Darts with auto trans came with 8 3/4 and ran 10 's . I don't know how many broke, but that's the way they came from the factory.
Greg
Wards Classic Car Radio Repair Specializing in restoration and sales of Mopar A B E body radios We can restore YOUR radio usually in less than 7 days Visit our NEW website.. http://www.wardsclassiccarradiorepair.comgregward@mchsi.comphone 256-852-0955
Posted By: hemiluver
Re: 8 3/4 strength poll!! - 08/27/08 01:15 AM
Thanks guys,
As far as launching the car I posted it in my first one but neglected to on this one. The cars a 68 RR 4spd 4:30's the car made 380 hp at the tire before I installed a Landy built 174 B&M supercharger with 6lbs of boost the car should make 670hp at the crank and a bit over 500 at the tire. I used to launch at 4k naturally aspirated but now roll out at 1800 to 2k due to tire spin. It now runs 28x11.5 Hoosier quick time pro's before I had MTs street ET's which were 1" narrower at the footprint. The cars best naturally was 13.01 I've yet to make a good clean pass blown. Sounds slow? But remember I'm at Bandimere in Colo with an alt of 5800 ft which after correcting ='s way over 6500 ft-You flat landers are lucky!By the way the car weighs 3730 with me in it!Thanks again-Gary
Posted By: JohnRR
Re: 8 3/4 strength poll!! - 08/27/08 01:18 AM
Quote:
Thanks guys,
As far as launching the car I posted it in my first one but neglected to on this one. The cars a 68 RR 4spd 4:30's the car made 380 hp at the tire before I installed a Landy built 174 B&M supercharger with 6lbs of boost the car should make 670hp at the crank and a bit over 500 at the tire. I used to launch at 4k naturally aspirated but now roll out at 1800 to 2k due to tire spin. It now runs 28x11.5 Hoosier quick time pro's before I had MTs street ET's which were 1" narrower at the footprint. The cars best naturally was 13.01 I've yet to make a good clean pass blown. Sounds slow? But remember I'm at Bandimere in Colo with an alt of 5800 ft which after correcting ='s way over 6500 ft-You flat landers are lucky!By the way the car weighs 3730 with me in it!Thanks again-Gary
That rear is on borrowed time , as you have already found out with your sure grip making weird noises .
Posted By: RUNCHARGER
Re: 8 3/4 strength poll!! - 08/27/08 01:32 AM
I've run these cars for 30 years. If I can buy a fairly bullet proof piece for a reasonable price I just don't know why I would spend almost the same price on a piece I would be wondering about. A dana is one of the best values for $$$ out there. You have a 4 speed, fairly heavy B-body with somewhat sticky tires. Do you really want to pump $500 or maybe $1000 into that 8 3/4 and wonder if it will last when you can put a new Dana in for $2k and be done with it?
Your car makes enough power to hurt that little 8 3/4 so you'll have to spend money upgrading it anyway.
Smallblock automatic in an A-body would be a different story.
Sheldon
Posted By: 383man
Re: 8 3/4 strength poll!! - 08/27/08 01:33 AM
My sons Dart runs 11.40's at about 3600 lbs and has had the same 8-3/4 in it since 1997. My 63 runs 11.50's and has had it's 8-3/4 in it for 2 years since I got it on the road. Both are stock rears with stock axles but I did put a Detroit Locke center section in mine. And both are auto's with Dynamic 9.5 converter's. It should hold up fine in a low 12 high 11 car and even better with after market axle's. Ron
Posted By: 383man
Re: 8 3/4 strength poll!! - 08/27/08 01:38 AM
I forgot you have a 4-speed as I agree that is alot harder on the rear then an auto. Ron
Posted By: RUNCHARGER
Re: 8 3/4 strength poll!! - 08/27/08 01:52 AM
Ron: Do you check your axles for twisting once in awhile?
Sheldon
Posted By: KillerBee
Re: 8 3/4 strength poll!! - 08/27/08 02:43 AM
My all steel 440 Sixpack powered 4 speed Challenger broke it's stock axle the VERY first time I took it to the track with ET Street tires.
I tried to launch the car extremely hard when the axle broke.
I replaced the axles with Moser ones and have ran the car a few more time at the track since without breaking anything but I have been doing much easier launches. My car has run a best of 11.80. I will definitely have a Dana under the car before any super hard launches again.
I think an 8 3/4 could be built(modified) to survive behind a 500-600hp automatic car(no trans brake) but NOT behind a heavy, 4 speed, big block car with sticky tires running at the track on a regular basis
Posted By: 383man
Re: 8 3/4 strength poll!! - 08/27/08 03:03 AM
Quote:
Ron: Do you check your axles for twisting once in awhile?
Sheldon
Actually yes we have. I had mine out this winter when I put the Locker in it and they are in perfect shape with no twisting. And we checked my son's last almost 2 years ago. Now his Dart has been raced a few times a year since 2000 and it had a mid 12 second 383 until 4 years ago when we put the 400 in it which runs mid 11's. I was very surprised as his axle's were perfect with no twisting at all. Now we dont race alot but he has raced it about 3 or 4 times a year. 
Ron
Posted By: 383man
Re: 8 3/4 strength poll!! - 08/27/08 03:06 AM
I think an 8 3/4 could be built(modified) to survive behind a 500-600hp automatic car(no trans brake) but NOT behind a heavy, 4 speed, big block car with sticky tires running at the track on a regular basis
Now that I do agree with. Ron
Posted By: jyrki
Re: 8 3/4 strength poll!! - 08/27/08 07:45 AM
Foot brake street cars, 10+ years of driving street & strip, all 8 3/4's with aftermarket axles, stock sure grips (both styles), most runs during this period in the low 10's with weights from 3240 to 3510, best ET's in the 9.4's with 1.39 60 ft times. Three cars, four rebuilds over all. One total gear breakage, others rebuilds were because of wear. At some point we backbraced them, and in one rear added cap preload bolts. Anyway, in my opinion they were pretty much trouble free. If you are starting with nothing and building a powerful car, I would go with something else. We chose Dana because it's less money, but now I wish I had gone with the 9". Lighter, easier to work on and everyone has parts for one.
Posted By: Qbird
Re: 8 3/4 strength poll!! - 08/27/08 01:26 PM
You guys need to brush up on your history a bit. The 8 3/4 was the first rear in the 5's...a mainstay in the Top Fuel cars right up to the early 70's. Keep in mind that spools didn't become popular until '72 or so, and up to that point it was pretty evenly split between open and sure grip diffs in the Fuelers. According to the spec sheet on Garlits first R/E car, it was rolling on 4:10 gears and stock Chrysler spiders.
Posted By: Neil
Re: 8 3/4 strength poll!! - 08/27/08 01:47 PM
How does one put down 1800 hp with an open rear end in a fuel car? All the videos and pictures that show the 60's and 70's cars smoking the tires down the track show both tires ablaze.
Posted By: Qbird
Re: 8 3/4 strength poll!! - 08/27/08 02:27 PM
Quote:
How does one put down 1800 hp with an open rear end in a fuel car? All the videos and pictures that show the 60's and 70's cars smoking the tires down the track show both tires ablaze.
Very narrow solid mounted rear goes a long way towards equaling traction. In a street car, you can preload the right rear with an air shock and accomplish the same thing.
Posted By: JohnRR
Re: 8 3/4 strength poll!! - 08/27/08 04:34 PM
Quote:
You guys need to brush up on your history a bit. The 8 3/4 was the first rear in the 5's...a mainstay in the Top Fuel cars right up to the early 70's. Keep in mind that spools didn't become popular until '72 or so, and up to that point it was pretty evenly split between open and sure grip diffs in the Fuelers. According to the spec sheet on Garlits first R/E car, it was rolling on 4:10 gears and stock Chrysler spiders.
Top fuel cars were running in the 5's in the early 70's ???
Ok guys sell your dana 60's and the rest of your safety equipment , the early pioneers of the sport did just fine without it ... it's a MONEY GRAB
edit .... oops , now i did it i questioned an icon of mopardom 
Posted By: Qbird
Re: 8 3/4 strength poll!! - 08/27/08 05:05 PM
Quote:
Quote:
You guys need to brush up on your history a bit. The 8 3/4 was the first rear in the 5's...a mainstay in the Top Fuel cars right up to the early 70's. Keep in mind that spools didn't become popular until '72 or so, and up to that point it was pretty evenly split between open and sure grip diffs in the Fuelers. According to the spec sheet on Garlits first R/E car, it was rolling on 4:10 gears and stock Chrysler spiders.
Top fuel cars were running in the 5's in the early 70's ???
Ok guys sell your dana 60's and the rest of your safety equipment , the early pioneers of the sport did just fine without it ... it's a MONEY GRAB
edit .... oops , now i did it i questioned an icon of mopardom
Go ahead and question me! Tommy Ivo ran the first 5 (426/8 3/4) but it was done at a match race and so it didn't count as official.
First official 5 was a 5.97 by Mike Snively in the Diamond Jim Annin T/Fueler (426/Dana). This was at the 72 Supernationals at Ontario. Same event, same day, Don Moody clocked at 5.91 (392/8 3/4) in the Walton Cerny Moody car.
There was alot of speculation at the time about hot clocks, but at the beginning of the 73 season 5's became common. I believe Garlits ran a 5.78 or so at Indy that year...also spit out a 250 that stood for some time.
At about this level, the 8 3/4 was starting to reach its breaking point. There was a guy that went by the name of Major Cooksey from Florida who was known as The Man when it came to T/F 8 3/4's...I believe there was an artical in Car Craft around 1972 that outlined his prep steps.
Posted By: ZIPPY
Re: 8 3/4 strength poll!! - 08/27/08 05:38 PM
Not to interrupt the John and Tony show....but
I run a Dana for 1 reason: I don't have a trailer.
The strip is an hour and a half drive...if the car ever broke there, the tow bill would probably cost the same as the axle, so I just did the axle and got it over with.
That said, the 8 3/4 held up great for me and took me from 13 flat to low 11s without any issues (other than paranoia setting in).
Posted By: 68Bullit
Re: 8 3/4 strength poll!! - 08/27/08 05:39 PM
No mention here of any types of 8.75 cases, such as the 489 case. Is it really stronger? Are some of the more extreme horsepower setups allowing the rearend to hold up because of a stronger 8.75 case?
Posted By: Qbird
Re: 8 3/4 strength poll!! - 08/27/08 05:54 PM
Quote:
Not to interrupt the John and Tony show....but
I run a Dana for 1 reason: I don't have a trailer.
The strip is an hour and a half drive...if the car ever broke there, the tow bill would probably cost the same as the axle, so I just did the axle and got it over with.
That said, the 8 3/4 held up great for me and took me from 13 flat to low 11s without any issues (other than paranoia setting in).
I've got nothing against the Dana...I've used plenty of them over the years, and if I was building a heavy stick car, that would be my first choice.
The discussion here was about the ultimate strength of the 8 3/4 and all I did was point out the most extreme applications for the rear.
I am currently building a twin engine Fuel Altered for myself, and decided to go with an 8 3/4 for a few reasons. With the direct drive/crowerglide combination in this particular car, I don't see shock loading to be a major issue. Also, with all the torque on tap, I don't see this car ever actually hooking up until waaaaay down the track.
Since this thing has two engines, I'm looking to save weight any place I can, and the 60 pound difference will help keep me under my target 2000 pound weight.
If I find that I can't get more than two or three passes out of the 8 3/4 I'll swap over to a Dana. Axles, brakes and whatnot will all swap over, so it's not that big of a deal to me. I can always use the 8 3/4 stuff in one of my street cars, so there's no waste.
Before anybody asks the obvious question..I have absolutely nothing against the 9 inch Ford...other than this car is going to be in MY garage. If I own it, it's going to be 100% Mopar.
Posted By: Qbird
Re: 8 3/4 strength poll!! - 08/27/08 05:58 PM
Quote:
No mention here of any types of 8.75 cases, such as the 489 case. Is it really stronger? Are some of the more extreme horsepower setups allowing the rearend to hold up because of a stronger 8.75 case?
It's not the case that is stronger, it's the style of pinion gear that's used in the various cases.
489 strongest, 742 next best and 741 is pretty much passenger car only.
Posted By: 68LAR
Re: 8 3/4 strength poll!! - 08/27/08 06:01 PM
If you want real life experience and input, here it is. My car weighs 3726 with a half tank of gas. Add another 200+ for me. 4 speed launching at 4K and 3900+ pounds. The 8 3/4 lasted many years until I started going faster. Once I hit the low 12's is when things started to come apart. U joints, the twisting axles, then bearing retainers, then twisting housings even after back bracing. I've had my dana in now for 3 years going on 4 and have not had one breakage. I could have saved a lot of money if I would have put the Dana in years ago, but I was a bull head. An 8 3/4 will last a lot longer with a light car and an automatic. A heavy car,a stick and slicks and you are living on borrowed time.
Posted By: Anonymous
Re: 8 3/4 strength poll!! - 08/27/08 07:41 PM
68LAR: I think that is the most factual post on here regarding the Poster's original question. An 8 3/4 can be okay but I think 68LAR's experience mimic what most have experienced. I've been lucky a few times finding twisted axles and other problems with 8 3/4's before they failed big time. That's in automatic E and B-bodies that were streetable, mostly low 12 cars.
Sheldon
Posted By: JohnRR
Re: 8 3/4 strength poll!! - 08/27/08 08:05 PM
Quote:
Quote:
Quote:
You guys need to brush up on your history a bit. The 8 3/4 was the first rear in the 5's...a mainstay in the Top Fuel cars right up to the early 70's. Keep in mind that spools didn't become popular until '72 or so, and up to that point it was pretty evenly split between open and sure grip diffs in the Fuelers. According to the spec sheet on Garlits first R/E car, it was rolling on 4:10 gears and stock Chrysler spiders.
Top fuel cars were running in the 5's in the early 70's ???
Ok guys sell your dana 60's and the rest of your safety equipment , the early pioneers of the sport did just fine without it ... it's a MONEY GRAB
edit .... oops , now i did it i questioned an icon of mopardom
Go ahead and question me! Tommy Ivo ran the first 5 (426/8 3/4) but it was done at a match race and so it didn't count as official.
First official 5 was a 5.97 by Mike Snively in the Diamond Jim Annin T/Fueler (426/Dana). This was at the 72 Supernationals at Ontario. Same event, same day, Don Moody clocked at 5.91 (392/8 3/4) in the Walton Cerny Moody car.
There was alot of speculation at the time about hot clocks, but at the beginning of the 73 season 5's became common. I believe Garlits ran a 5.78 or so at Indy that year...also spit out a 250 that stood for some time.
At about this level, the 8 3/4 was starting to reach its breaking point. There was a guy that went by the name of Major Cooksey from Florida who was known as The Man when it came to T/F 8 3/4's...I believe there was an artical in Car Craft around 1972 that outlined his prep steps.
thanks tony , stupid question though , how HEAVY were those cars ??? did they have TRANSBRAKES ??
as far as strength i feel the nod goes to the 742 over a 489 even with a solid spacer ... but that is just my opinion ...
Posted By: CrAzYMoPaRGuY
Re: 8 3/4 strength poll!! - 08/27/08 08:05 PM
Quote:
I've got nothing against the Dana...I've used plenty of them over the years, and if I was building a heavy stick car, that would be my first choice.
The discussion here was about the ultimate strength of the 8 3/4 and all I did was point out the most extreme applications for the rear.
I am currently building a twin engine Fuel Altered for myself, and decided to go with an 8 3/4 for a few reasons. With the direct drive/crowerglide combination in this particular car, I don't see shock loading to be a major issue. Also, with all the torque on tap, I don't see this car ever actually hooking up until waaaaay down the track.
Since this thing has two engines, I'm looking to save weight any place I can, and the 60 pound difference will help keep me under my target 2000 pound weight.
If I find that I can't get more than two or three passes out of the 8 3/4 I'll swap over to a Dana. Axles, brakes and whatnot will all swap over, so it's not that big of a deal to me. I can always use the 8 3/4 stuff in one of my street cars, so there's no waste.
Before anybody asks the obvious question..I have absolutely nothing against the 9 inch Ford...other than this car is going to be in MY garage. If I own it, it's going to be 100% Mopar.
Haha!
MY kinda guy!
I have nothing against the Dana rears either, great piece. I'll repeat that I started with a blank piece of paper with my Coupe, and money was no object to me, I went with an 8 3/4 rear too.
Posted By: Qbird
Re: 8 3/4 strength poll!! - 08/27/08 09:25 PM
Quote:
Quote:
Quote:
Quote:
You guys need to brush up on your history a bit. The 8 3/4 was the first rear in the 5's...a mainstay in the Top Fuel cars right up to the early 70's. Keep in mind that spools didn't become popular until '72 or so, and up to that point it was pretty evenly split between open and sure grip diffs in the Fuelers. According to the spec sheet on Garlits first R/E car, it was rolling on 4:10 gears and stock Chrysler spiders.
Top fuel cars were running in the 5's in the early 70's ???
Ok guys sell your dana 60's and the rest of your safety equipment , the early pioneers of the sport did just fine without it ... it's a MONEY GRAB
edit .... oops , now i did it i questioned an icon of mopardom
Go ahead and question me! Tommy Ivo ran the first 5 (426/8 3/4) but it was done at a match race and so it didn't count as official.
First official 5 was a 5.97 by Mike Snively in the Diamond Jim Annin T/Fueler (426/Dana). This was at the 72 Supernationals at Ontario. Same event, same day, Don Moody clocked at 5.91 (392/8 3/4) in the Walton Cerny Moody car.
There was alot of speculation at the time about hot clocks, but at the beginning of the 73 season 5's became common. I believe Garlits ran a 5.78 or so at Indy that year...also spit out a 250 that stood for some time.
At about this level, the 8 3/4 was starting to reach its breaking point. There was a guy that went by the name of Major Cooksey from Florida who was known as The Man when it came to T/F 8 3/4's...I believe there was an artical in Car Craft around 1972 that outlined his prep steps.
thanks tony , stupid question though , how HEAVY were those cars ??? did they have TRANSBRAKES ??
as far as strength i feel the nod goes to the 742 over a 489 even with a solid spacer ... but that is just my opinion ...
The typical T/F car of the era probably hit the starting line at about 1600 pounds (Fuel, oil, driver). Prudhomme fielded a car in 72 called The Yellow Feather, and if I remeber correctly, it was just a hair under 1200 pounds dry.
No transbrakes in those days. At the time the pack was pretty evenly split between pedal clutches and Crowerglides. Funnies of the era weighed about 300 pounds more and were using 2 speed transmissions. Diggers were still high gear only.
You've got me curious. Why would you choose the 742 over the 489. I've been gathering parts for this project and have 3 489 cases lined up for it. Think I'm going the wrong way?
Posted By: Anonymous
Re: 8 3/4 strength poll!! - 08/27/08 10:43 PM
The 489 is fine, just use a solid spacer rather than the factory crush sleeve.
Sheldon
Posted By: Qbird
Re: 8 3/4 strength poll!! - 08/28/08 12:06 AM
Quote:
The 489 is fine, just use a solid spacer rather than the factory crush sleeve.
Sheldon
Yeah, that's what I thought.
Posted By: 340duster340
Re: 8 3/4 strength poll!! - 08/28/08 01:37 AM
8.75 rear is plenty stronge, having built one from scratch, i woudlnt do it again. for the money i spent i could have had a 9inch or dana60...this was a few years back when prices were still stupid expensive, maybe it has come down a little since then, but next time i am going d60 or 9.
Posted By: JohnRR
Re: 8 3/4 strength poll!! - 08/28/08 04:08 AM
Quote:
The 489 is fine, just use a solid spacer rather than the factory crush sleeve.
Sheldon
The 742 inner pinion bearing has longer rollers and more closely resembles in size the inner pinion bearing of the dana 60 .
Not that MP has been the poster child of doing things right in the last decade or so but when they made the alum. center section for the 8.75 they decided to use the 742 gear set instead of the 489 gearset , there was obviuosly a REASON for that .
YMMV