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

Murilee Martin
by Murilee Martin

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.

Murilee Martin
Murilee Martin

Murilee Martin is the pen name of Phil Greden, a writer who has lived in Minnesota, California, Georgia and (now) Colorado. He has toiled at copywriting, technical writing, junkmail writing, fiction writing and now automotive writing. He has owned many terrible vehicles and some good ones. He spends a great deal of time in self-service junkyards. These days, he writes for publications including Autoweek, Autoblog, Hagerty, The Truth About Cars and Capital One.

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  • Commando Commando on Jul 19, 2013

    You, sir, are totally insane! PLEASE keep us up to date as this progresses.

  • Carbonfiber Carbonfiber on Jul 22, 2013

    Just a quick question why use a manual when a shift kitted auto with a shift at will kit if you plan on turboing and racing you will be at an advantage in having no loss of boost at gear change and a much faster shift

  • Golden2husky Have to say he did an excellent job on the C7, especially considering the limited budget he was given. I am very happy with my purchase.
  • Marty The problem isn't range; it's lack of electricity in multi-unit building parking. All you need is level 1 - a standard 120v wall socket - and if you're plugged in 10 hours overnight you get 280 miles per week or more. That's enough for most folks but you can use public charging to supplement when needed. Installing conduit circuits and outlets is simple and cheap; no charge stations needed.
  • 2manyvettes Tadge was at the Corvette Corral at the Rolex 24 hour sports car race at the end of January 2023. During the Q&A after his remarks someone stood up and told him "I will never buy an electric Corvette." His response? "I will never sell you an electric Corvette." Take that Fwiw.
  • Socrates77 They're pinching pennies for the investors like always, greed has turned GM into a joke of an old corporate American greed.
  • Analoggrotto looking at this takes me right back to the year when “CD-ROM” first entered public lexicon
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