By on July 19, 2013

02 - ZF Transmission Purchase - Pictures courtesy of Murilee MartinThe 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.
14 - ZF Transmission Purchase - Pictures courtesy of Murilee MartinKnown 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.
03 - ZF Transmission Purchase - Pictures courtesy of Murilee MartinThe 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.
06 - ZF Transmission Purchase - Pictures courtesy of Murilee MartinI 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!
08 - ZF Transmission Purchase - Pictures courtesy of Murilee MartinSo, into the hatch of my cargo-hauling, thief-magnet ’92 Civic with all the goodies.
07 - ZF Transmission Purchase - Pictures courtesy of Murilee MartinDid I mention that the transmission seller owns the nicest Jeepster Commando I’ve ever seen?
13 - ZF Transmission Purchase - Pictures courtesy of Murilee MartinI 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.
IMG_3240For now, the Plymouth’s body sits on wood blocks in the yard, awaiting its modernized frame.

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23 Comments on “’41 Plymouth Hell Project Puzzle Piece Scored Via Craigslist: Corvette ZR-1 6-Speed!...”

  • avatar

    I had a 1990 ZR-1. Those transmissions are sturdy, but they are Not Quiet… reminiscent of old tractors, actually. Too bad he didn’t get the LT5 with it — that would be a riot in a ’57 Chevy.

  • avatar

    I was pretty close with my 4+3 guess, this is the trans that replaced it!

  • avatar

    This is almost exactly how I would go about this entire build. I would probably end up with a 350Z trans, as they are plentiful and easy to find. I would have never thought that I could turn up a ZR-1 trans on Craigslist.

    Just promise me that LL8 is going to have a single, externally-vented wastegate dumping all 6 runners. That way, all the 2JZ fanboys can come up to you all confused when you pop the hood.

    As long as you’re being a trailblazer (pun intended), I would love it if you can dig up any engine mods they made to these things in SCORE trim, and integrate it into your build.

  • avatar
    bumpy ii

    “the plan is to buy a wrecked Trailblazer or Envoy donor vehicle,”

    You could buy Alex’s once the transmission grenades again.

  • avatar

    I am unreasonably excited about this project…

    • 0 avatar


      This is more interesting than anything currently happening in the auto industry.

      • 0 avatar

        My interest stems from the fact that I think the Atlas 6 should be a common swap for cars that originally came with I6 engines. Forget the SBC swap into your old Jaguar! Go with the Atlas I6! Why? Because you can keep that I6 Jag smoooooooooooothness while gaining reliability and 275 stock HP to boot! Plus you won’t be just another philistine who dropped a V8 in an XJ6. Dare to be different!

        • 0 avatar

          That makes the most sense of anything I’ve read all weekend. Seriously, why is a V8 always the only answer? People need to reawaken themselves to the pleasures of straight sixes.

  • avatar

    The ZR-1 specific ZF6 has a longer input shaft than the standard ZF in LT1/LT4 equipped C4’s. I would suggest double checking compatibility with your straight six if indeed that is a ZR-1 specific box.

  • avatar
    Piston Slap Yo Mama

    As thrilled as I am to see where this winds up – I’m still waiting for word on the Midget + Toyota 22R project. I suspect that somewhere along the line an announcement was made about this project being sold to a LeMons team as I haven’t heard about it in … years?

    • 0 avatar

      Rumor has it the ToyoSprite surfaced on the list of Craig recently…

      • 0 avatar
        Piston Slap Yo Mama

        SRSLY? I would totally have taken that Murilee project over had I known he was throwing in the towel. He really should document why he quit – is it that the 22R does not lend itself to the Midget engine bay or is it because MM is in Colorado while the car, I presume, remained in the locale of Alameda DOTS (Down In The Streets) era Murilee? Ah well. His current project (assuming it’s shepherded to completion) should be at least as interesting.

  • avatar
    Jeff S

    Keep us posted with pictures of your progress with the 41 Plymouth. Looking forward to a story from Crabspirits on this car. Maybe he can compose a story as to the last owner of this Plymouth junked it and its rebirth.

  • avatar


    I’m also following this with great interest, as I’m planning to swap a post-2005 LL8 into my Camaro. Although I’ll probably just put it in stock, with the 4L60E. For the sole purpose of keeping my “250” fender badges and the original column shift. The LL8 is something like 254 cubic inches, so it’s legit.

    I’ve found that donor vehicles are very hard to find in my area (Salt Lake City), even though there are like a billion of these out on the roads. I think your best bet is to find a friend or acquaintance with a business license (if you don’t have one yourself), and buy from the salvage auctions. I’ve seen several perfect donors on those websites, but don’t want to really hassle with the whole license thing.

    Have you looked at the oil pan thing yet? You might want to get started on that early on, too.

  • avatar

    This is stuff that I want to see more of on this site. Keep it up, can’t wait to see the outcome.

  • avatar

    As somebody who started a hot-rod project on a 1941 Chevrolet Special Deluxe back in high school (and ended up selling off all of the parts & pieces 10 years later), I will also be eagerly anticipating future updates!

    As an aside, here’s what I had collected to go into my project:

    – 283 SBC
    – Turbo 400 short-shaft transmission (and several drivelines)
    – 10-bolt Pontiac Firebird rear end
    – Corvair front crossmember (which was a popular swap before the now-ubiquitous Mustang II conversions)
    – Cadillac Tilt-Tele steering column
    – Buick Riviera split bench power front seats
    – NOS Aftermarket under-dash A/C unit

    I spent a few years going to swap meets selling everything off. I love old cars, but life happens. It’s enough to vicariously enjoy somebody else’s project for now!

    • 0 avatar

      I wonder how many dads put up with all that going on in their garage? A friend of mine wanted to drop a big block Mopar into a ’53 Plymouth Cranbrook coupe, but his dad lost patience after 3 months and took over the project. My friend ended up a couple months later with a 2bbl 273 and torqueflite auto, column shift and bench seat, all taken from a ’67 Valiant. It was definitely faster than the original flathead six and 3-speed “standard”, but not what my friend envisioned. The car ended up as his dad’s daily driver, and his dad bought him a ’69 Ford Cortina.

  • avatar

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

  • avatar

    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

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