’41 Plymouth Hell Project Puzzle Piece Scored Via Craigslist: Corvette ZR-1 6-Speed!

The 1941 Plymouth Special Deluxe sedan Junkyard Find that I bought from the Brain-Melting Colorado Junkyard last fall now has the body off the frame and is awaiting a Lexus SC400 suspension subframe swap. After much debate about what engine/transmission combo to use in this Hell Project (the plan is to build it to Pikes Peak International Hill Climb specs, while retaining a grimy-looking rat-roddish character), I decided to go with the GM Vortec 4200 aka LL8 L6 engine, with turbocharging added, and that meant that I’d need to find a manual transmission that can withstand at least 400 ft-lbs of torque. Since the Vortec 4200 never came with a manual transmission, and the pseudo-bolt-on Aisin-based 5-speed out of the Solstice and Colorado can’t take the sort of power I’m hoping to get (thus forcing me to go the machine-shop bellhousing-adapter/custome-flywheel route), I was looking for a Borg-Warner T-56 out of a fourth-gen GM F-body, or maybe a Tremec TKO out of a fourth-gen Mustang. Then, an ad for a ZF S6-40 6-speed showed up on Denver Craigslist, with a very reasonable asking price.
Known as the “Black Tag” ZF transmission, this rugged German 6-speed was used in C4 Corvette ZR-1s and is rated for up to 450 ft-lbs of torque. Thanks to its square-cut gear teeth, this transmission made more noise than many Corvette buyers could tolerate, and so GM went to a quieter gears and (if you believe the rants of detail-obsessed Corvette freaks) less strength for the 1994 model year.
The seller of this transmission had purchased it out of a wrecked ’93 ZR-1 for use in this beautiful ’57 Chevy project, which is getting an LS swap, but the ZF turned out to be too big to fit in the Chevy without major transmission-tunnel hackage.
I brought along Rich, the guy I’ve hired to do the engineering and fabrication work on the ’41 Plymouth project, to check out this transmission and say yea or nay on the possibility of using the ZF. He’s the captain of the Index of Effluency-winning Rocket Surgery Racing Checker Marathon 24 Hours of LeMons team, and he managed to get a small-block Chevy engine to bolt up to a Ford Toploader transmission and then stick the resulting mess into the Checker using all manner of garage-expedient cheap technology The ZF transmission came with all the little bits and pieces that make a Frankensteinian swap like this a lot easier, including the shifter, clutch master/slave cylinders, bellhousing, flywheel, even a bag full of fasteners. Looks good!
So, into the hatch of my cargo-hauling, thief-magnet ’92 Civic with all the goodies.
Did I mention that the transmission seller owns the nicest Jeepster Commando I’ve ever seen?
I haven’t bought the Vortec 4200 yet (the plan is to buy a wrecked Trailblazer or Envoy donor vehicle, so I can get all the harnesses, computers, and maddening little bits needed for the planned swap), but we’ve got this block and pan to enable Rich to move forward on the necessary fabrication on the Plymouth’s frame.
For now, the Plymouth’s body sits on wood blocks in the yard, awaiting its modernized frame.