Guys,

I have been thinking for awhile on how I could up the fun factor on my 1973 Charger. One of the things that grinds on me with this car is the high rev's on the highway and just being not as fun as it could be for longer trips.

I am also an appreciator of a good strong motor and a manual tranny. Therefore, I wanted to start doing some research on maybe doing a conversion from my current 727 to a TK600 or T56.

Here is what I have now:

- 1973 Charger mild BB 500 stroker (original motor) ~500hp/550tq
- non original 727 auto tranny (was a 727 car just original tranny was destroyed)
- 8.75 rear with Auburn limited slip unit 3.55 gear 28" tall street tires


I have looked a little on SST an Hurst's websites and I have some questions and need some input from those who have done this.

Of course, I would prefer the T56 over the TK600 but what concerns me is it appears you have to cut the entire frame to squeeze it in there. I am ok doing work on the tunnel but not so OK with cutting the frame on this mostly original car.

So, for those who are familiar with these swaps, can the TK600 be installed without cutting the frame? I understand no matter what the tunnel has to be patched but I REALLY don't want to butcher the frame plus I would think that might compromise the structure of the car...

Also, is the TK600 worth it or would I really be wishing I had gone for the T56?

My goals here are:
- no frame cutting (if that's possible)
- fun factor (decent OD for cruising)
- factory-looking shifter setup
- will live behind this motor with street tires

Also, has anybody here actually done this swap and can tell me the cost for the whole deal? This is an auto car so I would need EVERYTHING pedals, slave cylinder, clutch, bellhousing, etc. I am guessing in the 4-5K range?

Or should I leave this alone and not cut into this mostly original car at all?

Any input is appreciated!

You will need to cut to keep the driveshaft angles right.

So for both transmissions, you have to cut the frame?

Have you considered the Gear Vendors unit that bolts to your 727? I have no experience with them, just know they're an option...

They are only a .8 overdrive IIRC and you still have to enlarge the tunnel/shorten the driveshaft.

I also think you have to have some switch/button rigged up to control the OD?

Might be an option but I would prefer a manual TBH.

passon performance a855 but you gotta wait about 1 year

Ive heard this exact comment 3 or 4 years ago.
Ive got 2 clients gave up and moved on

Yeah I'm not waiting on that. I have heard that "one year away comment" since 2011 at least.

Even though it is a physically larger trans in all dimensions than the TKO, I think you will really want/like the T56-Magnum better. I know for sure it shifts better than the TKO esp. at high(er) rpm.

My goals here are:
- no frame cutting (if that's possible)- not possible with either trans
- fun factor (decent OD for cruising)-- either one ok T56 double OD 5th & 6th
- factory-looking shifter setup - someone else will have to answer
- will live behind this motor with street tires - T56 is better IMHO

with 500cid/500hp/550tq 1st & 2nd gear will only be needed when you want to show off. TKO/T56 both have really deep 1st gears, and only slightly less deep 2nd gears, you will be able to spin the tires very easily. You will probably find that starting off in 2nd works just as well then a quick shift into 3rd for everyday/non-spirited driving.

I can let you know here soon. I just ordered the TKO 600 from SST to install in my '72 Charger. It is expected to ship the day after Christmas.

I was under the impression the TKO600 could make it in there without cutting but I guess I was mistaken. I am still curious as to if this cut would compromise the car's structure or not? It seems if this had no purpose, the factory would not have put it there.

This car is a restomod. It is pretty much original except the following:
- changed color (originally light blue)
- aluminum radiator
- electric fans
- Sandon AC compressor
- the normal bolt-on performance goodies (headers, FF steering gear, aluminum heads, rear gear, limited slip diff, Holley carb, etc.)
- had to replace the transmission case and most of the innards years ago (transmission was WRECKED when I bought the car)

I know this is not a 69 R/T but would I be killing the car's value to make this significant mod to it? I just feel this will kill some of the "number's match" aspect doing this.



Id your car a 727 car or a 4sp already? What was the cost of the kit if you don't mind me asking?

in terms of value, unless your car is a one of hemi something, you won't be losing much. collector value is just that. fun value is whole nother thing. will someone value the mods you did probably not, will you enjoy them more and the car more when you do them? if so do it. there really isn't anything that can't get undone these days.

Factory 318 column shift. Request a quote from SST. You’ll have it in a day or two.

So no other input or experiences with this swap? I figured there must be quite a few here who have done this before.

So if my desire to not cut the frame is unrealistic, what strengthening will need to be done to compensate for this, if any? I just don't want the car twisting all over the place if it hooks..

Also can anybody vouch for SST or share any experiences with using their PerfectFit kits? I know other vendors have similar setups - should I be reaching out to them?

Maybe SST has cured the issue with the TKO and the crossmember? IDK.

The problem before was to make it a "no cut" install you had to let the back of the trans hang down further than stock. This of course tilted the engine back further than stock. This led to driveshaft angle/U-joint angle problems with the rear axle, exhaust pipe connection if stock and header collector problems if you went that way.

Look around here, or google for, pictures of the TKO, T56, and Chrysler 833 transmissions and you will see that the TREMEC trans have much more structure on top of the trans than did the 833. What used to fit under the floor now doesn't. Once you see both a T56 and a 833 side by side the 833 looks down right small in comparison.

The part of the "frame" that needs to modified is fairly small, the lower trans crossmember that unbolts from the car and the upper hoop that goes over the trans and under the floor. There was a thread on here w/in the last 3 months that had some good pictures but I couldn't find it. But the hoop section need to be cut out, made taller and wider, just by a bit, and reinstalled along with floor patches to cover the new/extra space you just made.

In the 73-4 Chargers you also have the rear torsion bar anchor member to remove as well to get the trans out/in. Someone else will have to report on if that needs any modifications for additional space.

These are some threads with pictures that I did find, non for 73 Chargers but it helps give you an idea of what your looking at.

https://board.moparts.org/ubbthreads/ubbt...-automatic.html

The second picture shows the hoop above the trans that need to be modified.
The next to last picture shows his mock up of the bolt in trans crossmember that he has made.

While the thread is about an auto 518 install it gives you some idea of the problems of putting a larger trans in place of the stock one.

https://board.moparts.org/ubbthreads/ubbt...y-question.html

This thread shows the problems and a potential solution to the TKO problem but instead of cutting the car he trimmed/cut the transmission.

I have a 71 RR, and I went with a passion 4 speed OD, and really like. With a big inch high torque motor, it is really nice. You use all factory parts, so it bolts together like factory, and no cutting. That alone makes it a no brainer. No mix matching of parts, if you need something, then just get a factory part. I cruise on the highway around 2500 and between 75 and 80. I think his 4 speeds are readily available.

There is a lot of "girth" at the rear of these Tremec transmissions and you will probably have to cut and box the torsion bar crossmember. I re-built a few of these transmissions and compared them to an 833 and my Richmond 5-speed while it was on the bench. The T-56 was was about 5 inches wider at the mount than the 833 and 3 inches wider than the Richmond.
I really liked the Richmond 5-speed but you have to cut and box the torsion bar crossmember and fab your own transmission crossmember.
There are probably over 100 posts about the Keisler/SST conversions and what needs to be cut and fabbed.
Gus

I would either get the Passon 4 speed OD or a T56 magnum.
A TKO is not worth cutting up your car. T56 is a much better trans overall and is a 6 speed.
I had a TKO600 and sold it.

Just one last "bump" for ya. I was kinda hoping to see member "Goodysgotacuda" chime in as he recently put a T56 in his '73(ish) Cuda. I know it's not a "B" but his experience might be helpful. Maybe send him a PM if he doesn't chime in...

Yeah I got the quote back for both the TKO and T56....quite pricey and way more than I expected.

I have to do some soul searching to see if I want to drop that kind of dough and still have to cut into my car.