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A500 all the way....

1) A500/42RH has the low first/2nd vs. an older 904 (2.74/1.54 vs. 2.45/1.45)

2) A500/42RH has a lockup torque converter to help drop cruise RPM

3) A500/42RH has a .69 OD ratio vs. .78

4) newer 42RH's have an improved converter hub design that is much less likely to crack (and that I'd recommend looking for)

IIRC on later B's, with some trimming of the ribs on the OD tail section, there is no floor pan/tbar crossmember cutting required, but you'll have to make your own lower bolt on mount/crossmember

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Too big at the rear.

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Too big at the rear.

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a500 and 518 tail sections are the same. they will fit under a stock late B and E body floorpan with some trimming of the external case ribs.

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I would pull a A500 from a junkyard truck for 100 bucks and pocket the rest. Or spend some of the money and rebuild/upgrade the A500. The 500 has a better overdrive ratio than the gear vendors and can be done substantially cheaper if you build the trans yourself.

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The option that I highly recommend for your application is our StreetPro 727A with the "Shortie Overdrive" option. This unit is only 7 1/4" longer than your 727 and is a direct bolt-in (other than driveshaft shortening).

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The GV unit will take 0hp away from your normal 3 speed operation where as the A500 is always robbing some hp because it drives thru the OD all the time. They say it can rob as much as 1sec in ET...

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Before I committed to it I asked around if this transmission would be a good choice for a motorhome (weighs 6500 pounds) and was told that the overdrive part would be too weak for this application. I ended up just building a standard 727. I would have liked the extra mileage. Now I have a new '74 camper which is around 7000 pounds and interested in overdrive again but this rig already has a good 727 in it and wonder if this shortie overdrive would work.

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So they didn't think the 518 would work in a 6500-7000lb motor home but it works just fine in dodge pickups that weigh 5000lbs on their own + tow that much in trailers, cars, campers, etc. A good rebuild kit and the transgo tfod-hd2 shift kit is the ticket. With the right combination of parts you can also install extra clutches in the overdrive tail unit.

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The GV unit will take 0hp away from your normal 3 speed operation where as the A500 is always robbing some hp because it drives thru the OD all the time. They say it can rob as much as 1sec in ET...

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I have never seen one scrap of evidence to back up this claim. Not saying it's impossible, but I have never seen anything to substantiate this at all. Until I see a real, all things equal comparison between the two, I'm going to have to put this one right up there with the other myths like the thin wall 70's 440 blocks and low nickel late 70's mopar blocks.



smr transmissions did a comparison on a small block dodge dakota between a 727 and a 518. Lost a full second e.t. with the 518. Same truck, engine, rear and track.

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Here is the shorty..

http://smrtrans.tripod.com/smrtransmissionsintro/id32.html

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THE "Shortie" overdrive option can be added to any of the above transmission models for the additional cost of $2,825.00.

I just lost interest!

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Here is the shorty..

http://smrtrans.tripod.com/smrtransmissionsintro/id32.html

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THE "Shortie" overdrive option can be added to any of the above transmission models for the additional cost of $2,825.00.

I just lost interest!

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smr transmissions did a comparison on a small block dodge dakota between a 727 and a 518. Lost a full second e.t. with the 518. Same truck, engine, rear and track.

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I'm sure a company that specializes in 727 and 904 AND sells the gear vendors units is absolutely unbiased.

Where's the data? Specs on the transmission builds? Was this a bone stock w/ stock converter 518 left in drive versus a 727, converted to roller internals with an aftermarket converter, valve body and shifted manually?

Take a stock unrebuilt 727, stock unrebuilt non-lockup 518(so you can put the same converter on both) and actually rebuild both transmissions COMPARABLY. Then run then down the track 10 times each and get back to me. Until someone does that, everything is heresay and myth.

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smr transmissions did a comparison on a small block dodge dakota between a 727 and a 518. Lost a full second e.t. with the 518. Same truck, engine, rear and track.

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I'm sure a company that specializes in 727 and 904 AND sells the gear vendors units is absolutely unbiased.

Where's the data? Specs on the transmission builds? Was this a bone stock w/ stock converter 518 left in drive versus a 727, converted to roller internals with an aftermarket converter, valve body and shifted manually?

Take a stock unrebuilt 727, stock unrebuilt non-lockup 518(so you can put the same converter on both) and actually rebuild both transmissions COMPARABLY. Then run then down the track 10 times each and get back to me. Until someone does that, everything is heresay and myth.

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The 518 can in no way rob more HP than a GV. The 518 only adds roteing weight in 1st 2nd and 3rd, no other "drag" is added, the pump is not doing any work holding clutches or bands or line preasure or any thing. The GV adds a similar amount of rotateing weight in all gears combined with an almost useless extra gear. The OD section can easily have clutches added, if you use the 48RE OD section it can handle 800 lbs tq easily!

As for the 1 second difference in ET from a 727 to a 518 I say BULL CRAP! Like I mentioned earlier, there is a few pounds added to the rotateing weight, thats IT! In first second and third there is some extra weight and in no way can those few extra pounds knock off 1 second in ET. If the trannys get equal prep it can't be more than a couple tenths. If 5-10 pounds in rotateing weight could really knock off 1 second then every car could switch from a steel drive shaft to carbon fibre and gain a second

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Show us the math on the "worthless extra gear". I'll even give you the parameters. 3.73 rear gear, 28" tall rear tire, 4000lb car.

Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

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The 518 can in no way rob more HP than a GV. The 518 only adds roteing weight in 1st 2nd and 3rd, no other "drag" is added, the pump is not doing any work holding clutches or bands or line preasure or any thing. The GV adds a similar amount of rotateing weight in all gears combined with an almost useless extra gear. The OD section can easily have clutches added, if you use the 48RE OD section it can handle 800 lbs tq easily!

As for the 1 second difference in ET from a 727 to a 518 I say BULL CRAP! Like I mentioned earlier, there is a few pounds added to the rotateing weight, thats IT! In first second and third there is some extra weight and in no way can those few extra pounds knock off 1 second in ET. If the trannys get equal prep it can't be more than a couple tenths. If 5-10 pounds in rotateing weight could really knock off 1 second then every car could switch from a steel drive shaft to carbon fibre and gain a second

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Show us the math on the "worthless extra gear". I'll even give you the parameters. 3.73 rear gear, 28" tall rear tire, 4000lb car.

Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

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The 518 can in no way rob more HP than a GV. The 518 only adds roteing weight in 1st 2nd and 3rd, no other "drag" is added, the pump is not doing any work holding clutches or bands or line preasure or any thing. The GV adds a similar amount of rotateing weight in all gears combined with an almost useless extra gear. The OD section can easily have clutches added, if you use the 48RE OD section it can handle 800 lbs tq easily!

As for the 1 second difference in ET from a 727 to a 518 I say BULL CRAP! Like I mentioned earlier, there is a few pounds added to the rotateing weight, thats IT! In first second and third there is some extra weight and in no way can those few extra pounds knock off 1 second in ET. If the trannys get equal prep it can't be more than a couple tenths. If 5-10 pounds in rotateing weight could really knock off 1 second then every car could switch from a steel drive shaft to carbon fibre and gain a second

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Show us the math on the "worthless extra gear". I'll even give you the parameters. 3.73 rear gear, 28" tall rear tire, 4000lb car.

Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

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the worthless extra gear comment meaning this:

3rd (direct) at 75mph with 28" tires and 3.73 assuming no converter slip: 3350 RPM, mist likely 3500 w/converter slip

gear vendors OD drops it to 2650 RPM no converter slip, most likely 2800-2850 with slip

518 OD drops it to ~2320 RPM, with no converter slip. you won't have converter slip if using a lockup converter...

IMHO a .78 OD is not enough OD to warrant the cost... [/quote}

Cost aside - 700 rpm drop is not worthless. The 518 is better from that standpoint, but what option do you have if you don't want to hack up your car? Keisler GM adaptation? Better first ratio and as good or better O/D ratio.

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Also has anyone factored the cost of modifying the trans tunnel or the loss of perceived value with a hacked up cross member?

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Well if you can't manage the tunnel/crossmember mods yourself, then chances are you can't fab your own trans mount for the 518, and chances are you can't build your own 518 either. So if you have to farm all that out, you are probably at the same $ level as a gear vendors.

FWIW, the OP asked about a 72 charger. A 72 charger will not need the tunnel or crossmember modded. A 70 or earlier b-body would need those mods. If you have a car that would need the crossmember modded, and you're not comfortable with that, then yes chances are you would be happier with a gear vendors or a chevy 700r4 based auto like the keisler 4-sp auto. Also, from what I've gear, the gear vendors units still do require you to your tunnel for clearance. You don't have to and but it's not a straight bolt in either from what I've read.

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Cost aside - 700 rpm drop is not worthless. The 518 is better from that standpoint, but what option do you have if you don't want to hack up your car? Keisler GM adaptation? Better first ratio and as good or better O/D ratio.

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Cost aside - 700 rpm drop is not worthless. The 518 is better from that standpoint, but what option do you have if you don't want to hack up your car? Keisler GM adaptation? Better first ratio and as good or better O/D ratio.

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I would add Gear Vendors for one simple reason. I don't think MYSELF would change an original part of my car, just making upgrades. Gear Vendor is an upgrade of the original part, is an ADD ON section on my original tranny.

Otherwise, I think there is not 727 replacements with OD for BBs... or yes ?

But that's me

anyway, I can't afford it LOL

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What about the 200r4? Same ratio as the 904 w/low gear set and a nice .67 od. Can handle a good amount of power when built right. And no tunnel mods, just need to redo the cross member.

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What about the 200r4? Same ratio as the 904 w/low gear set and a nice .67 od. Can handle a good amount of power when built right. And no tunnel mods, just need to redo the cross member.

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Yes, the GM 200-4R or the 700-R4 can be used. The 700 has the lower 3.00 first gear and the 200 has a 2.75 I think. Both are still lower than any stock 727. Either one can be built to handle a good amount of power and both are small enough to not require any crossmember or floor pan mods. You will still need to fab your own trans mount however. I think the only other real issue with those transmissions is you will need an aftermarket shifter. Their shift pattern is is PRND321 where the gear vendors and 500/518 have an electronically activated overdrive gear and will mate up to your stock shifter.

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What about the 200r4? Same ratio as the 904 w/low gear set and a nice .67 od. Can handle a good amount of power when built right. And no tunnel mods, just need to redo the cross member.

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Yes, the GM 200-4R or the 700-R4 can be used. The 700 has the lower 3.00 first gear and the 200 has a 2.75 I think. Both are still lower than any stock 727. Either one can be built to handle a good amount of power and both are small enough to not require any crossmember or floor pan mods. You will still need to fab your own trans mount however. I think the only other real issue with those transmissions is you will need an aftermarket shifter. Their shift pattern is is PRND321 where the gear vendors and 500/518 have an electronically activated overdrive gear and will mate up to your stock shifter.

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Wilcap makes an adapter for this app.. I will use a floor shifter any so that will be taken care of. And yes you will need to make a trans mount, but how hard can that be, the 518 you need to do this also.

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I know the chrysler OD will need a mount fabbed, just the way the generic trans option was stated it sounded like there was no fab work needed, I just wanted to clarify

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Fab work is definitely needed for the chevy transmission, along with an adapter such as the wilcap plate mentioned. However if a person has a car in which a 500/518 won't fit without modding the crossmember, and if said person is dead set against that, doing a bit of extra work to get the chevy transmission to work would more likely to be worth it to them than it would be to you or me. I would sooner just mod the crossmember if it really needed it, because none of my cars are worth much anyway, I'm not scared of modding and it's not visible after.

You say the 200-4R is the weaker one, others online say the 700-R4 is the weaker one. I don't know who is right, I've heard claims both ways. I don't really care because I'm not in the market for either of those transmissions anyway. I know both of them will need more upgrades dumped into them to holdup behind a big block, where a 518 with a race rebuild kit and that transgo shift kit will do the job. To run the GM trans, at a minimum you will need a new driveshaft, trans adapter, fab trans mount and an aftermarket kickdown cable. Not sure what speedo cable will mate that trans up to your stock speedometer but I'm sure there's one. The point is it can be done with a reasonable amount of work.

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from what i understand the 200 you only have to mod the bolt in part of the cross member. the 518 you have to cut the hell out of the upper ( welded to the floor) part of the cross member. the 200 would be a lot easier swap then the 518 in my opinion.

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