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Discussion Starter · #1 ·
Ok guys, I got asked to post what mods is necessary to put a mopar 4 speed behind a chevy engine. You will need an adapter plate to begin with that bolts to mopar trans and in turn the adapter bolts to the chevy bellhousing. The one i have is a vintage Lakewood piece from the 70's and has been out of production for years. The only place i know of to get one is from passon performance, I have talked to Jamie Passon before and he says they have the plates.
You will need to cut 3/4 inch off the pilot on the input shaft and then turn down the remaining pilot to fit a chevy pilot bushing. The next step, which is where I'm at right now is getting the chevy TO bearing to fit the mopar bearing retainer snout. The chvery bearing has a larger ID then the mopar. My buddy has done this b4 so it wont be a big deal. Take some fairly thick walled tubing that fits the mopar snout snug enough that it has to be pressed on. The turn it down in the lathe to fit the chevy bearing. I haven't asked, but Passon may carry a bearing retainer already setup this way to simply things.
Now of course you will have to modify the crossmember in your ride to accomadate the mopar trans. I will post pics of mine for my 64 impala as soon as i can. I had to remove material from the front of the crossmember to clear the main case on the trans. Then I took some 1/4 in flat and welded it to the x member and bolted it to the trans. Plate was about 8 inches long and 6 inches wide but will depend on your app.
I was able to use the factory chevy rear trans mount, just had to come in 1.25 inches on each side and drill new holes. Bolted to the mopar trans perfectly but took a wrench to do this because clearance gets pretty tight.
Last you will have to mount the trans in the car to locate where the shifter placement will need to be. I built my own bracket based off a picture of the bracket that was used by mopar in some B body bench seat apps.
Guess that does it guys, any ? just ask, I'm always glad to help and I will get some pics up as soon as i can get my lovely wife to take them:cool:
 

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Discussion Starter · #6 ·
Thanks Isaac! I'm with ya. The mopar trans will be a unique addition to my impala plus i know it handle the abuse i'll put it through. I'v been shifting the mopar 4 speed for over 10 years now and feel comfortable with them.
Good stuff. I like the run what you got idea.
 

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Thank you Casey for writing that. I gather then that the Mopar input shaft is much longer than the GM shafts if you are using the adaptor and still cutting 3/4 inch off of the pilot tip. But these are the things that are not readily apparent to someonelooking at doing a modification like this in the future. Your experiences and work helps everyone a lot. Good write up. Mark L
 

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great article, a buddy of mine has been trying to convince me to change out my M-21 for a new process and this article will make it easier to do when the time comes.

Charlie
 

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Discussion Starter · #12 ·
great article, a buddy of mine has been trying to convince me to change out my M-21 for a new process and this article will make it easier to do when the time comes.

Charlie
Glad to help. Let me know if you need any more info. The mopar trans is definately tough
 

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Are the benefit's of this just a stronger trans? I have a M21 from a 71 pontiac I was gonna put behind my Olds but this is rather interesting.
 
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