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Ok I tried asking someone I thought would know but apparently it’s a trade secrete .
Does anyone know how I can get a 4bt Cummins to work in my m37 the thing I don’t understand is ether what tranny to use on how to get the stock tranny to work with this motor. Any help\ideas are welcome.
Thanks

Have you done a web search. There are a bunch of websites that have 4BTs in an M37. Most use the transmission that came with the motor. Or if the motor came from a chevy bread truck (most common) they may switch from a chevy auto to a chevy stick.

Here is one such site....http://www.garbee.net/~cabell/

There are a few more just google or yahoo M37 cummins and see what you get.

Here's a forum dedicated to the 4bt:

http://www.4btswaps.com/forum/index.php

HTH.

John

After some searching on my own the most common transmission seems to be the NV4500 for a stick and the 700R4 for an automatic.

I like the NV4500 because it's a five speed so it could give you some cruising speed....if you change the rear end to a lower ratio....

An overdrive unit between the trans and the t-case would be a wonderful thing. So would the trans out of my '79 or '97 Dodge vans. They had a 4-speed floor shift in 'em, with 3rd gear being 1:1 and 4th being overdrive. Either would be good.

k8icu wrote:if you change the rear end to a lower ratio....

Where can I get gears that won’t be so low?

Well....That's the hard part...finding 4.89:1 ring and pinion.... I think Charles (Mseriesrebuids) has some he may part with. MARS says they have them, but there website is "under construction" and they wont return phone calls and the e-mail doesn't work...so who knows. I don't know if Ray at Uglytruckling has them....It is my understanding that you can take the diffs out of a civy dodge truck of the erra and swap them in so maybe Vintiage Powerwagons might have some. ...but I'm just guessing. Maybe someone else will add some better info.

I have 4.89 gears & offer complete installations & rebuilds if you desire.