I'm really surprised to see that fancy clutch pedal setup is available for a C body. I wonder how many they have sold so far?
Assuming you have some fabrication skills, I doubt that you'll have much trouble installing a TKX in a C body. Due to the 727 automatic being such a large transmission, Chrysler products have generous sized transmission tunnels compared to many GM cars that only needed room for a Powerglide trans. The TKX will likely fit without having to add a 4 speed hump to the floor, since there's no external linkage on the left side of the trans to deal with. I'd bet that the changes you'll have to make to the trans crossmember will be fairly minor too. The mount will probably be moved to the front of the crossmember and will be lower than stock. If your car is still assembled, I recommend finding out the angle that your engine sits at before taking things apart so you'll have a reference for when you're mocking things up. Don't install the pilot bearing in the crank until after you have your crossmember built. That will make it easy to shoot the trans in and out of the car as you figure things out. Access to a drive-on lift is a major plus. It's the best way to measure all your driveline angles.
The absolutely most critical part of a Tremec install is to get the bellhousing properly indexed to the crankshaft centerline. The TKX has tapered roller bearings supporting the input shaft, and there is
NO freeplay in the shaft like the earlier 4 speeds have. If it's not indexed properly there will be shifting issues and can quickly destroy the trans. There are loads of videos on You Tube about indexing bellhousings, and they're all wrong. They all do concentricity first and parallel second. You want to correct for parallel first
then check for concentricity. The machining on the bellhousings is quite good and the problem is usually the back of the block is not perpendicular with the crank. You can buy shims on ebay to correct parallel.
I make it clear on the bellhousing that shims are needed and where they go. The writing isn't visible once everything is back in the car.
I just finished up a TKX install in a 1963 Impala at work and did another on a 1956 Corvette earlier in 2025. Both of these car have "X" frames, which complicated the installation process.
The Corvette has a ladder frame that uses an X in the middle as a stiffener. The X is right behind the transmission and prevents you from moving the trans back enough to get it in and out of the car. Starting in 1958 Chevy moved the X back a few more inches to fix this issue. On our '56, we simply removed the engine and trans as a unit, doing the same when things went back into the car. The engine needed to come out for a bit of a freshening anyway, so removing both was no concern at all. I did the indexing with the engine partially supported by our engine run stand, along with the engine hoist.
You'll need a decent dial indicator with a magnetic base.
I hadn't yet discovered the special bellhousing shims when I set up this trans and instead purchased small round shims from McMaster-Carr. I recommend the special ones, as they have much more surface area.
On a Chevy, the Tremec bolts right up to the original 1956 steel bellhousing and can retain the stock clutch linkage and flywheel. Mopar requires special parts to adapt what's basically a Chevy trans to the Chrysler engine.
An engine tilter is a must when removing and installing the engine and trans together.
Although the TKX was specifically designed as a replacement for the classic 4 speeds, the top of the trans is higher, and that's were you're likely to run into fit issues.
Other than a custom trans crossmember and a shorter driveshaft, the only modification required on the early Corvettes is to slice a 1/2 inch section out of the ash tray pocket in the trans tunnel next to the shifter.
Trans installed in car. Stock spedo cable screws right on.
The '63 Impala was a bit more involved. The instructions From Silver Sport were for the TKO and TKX and have a dubious warning on the front cover stating that modifications to the body and frame may be required. I was able to install the trans after a little "massaging" of the trans tunnel with a big hammer. We also had to purchase a thousand dollar custom driveshaft because the '58-'64 X-frames use a 2 piece shaft with center support bearing. We now have it all back together and working, though my driveline angles aren't ideal. My u-joint angles are 4.5 degrees, where 1 to 3 degrees is preferred. We need to do a high speed run to test things out, but that's going to have to wait till it gets a bit warmer out.
There's plenty of You Tube videos on putting the TKX in a Mopar. I would watch them all to see what tips you can pick up. 1968-70 B body would be the most relevant, as they are closest to the slab C's in design.
Jeff
