gm th400

gm th400


1980 Jeep CJ7,304 with a th400 automatic transmission, amc 20 in the rear dana 30 front and a dana 300 transfer case
I have been searching the forum with no luck to find out if the Jeep th400 is the same as the one that came in the camaro years ago ...or.... if they are do they bolt up the same
Also if anyone has a link to someone that has switched an auto trans to a stick please send it to me
As always I appreciate all the help
The TH400 used in quadra-trac equipped Jeeps had an AMC-specific case with an AMC patterned bellhousing and is not interchangeable with the GM TH400's without an engine to tranny adapter. The early pre-AMC TH400's used the BOP bolt pattern and had a factory adapter to make them fit the 225/327/or Buick sourced 350 in the respective jeep. That adapter will not fit an AMC patterned block.

The TH400 was used in '72-'73 Commandos as well as '72-'76 FSJ's with AMC engines and Dana 20 transfer cases. I am 75% sure that they also used an AMC-specific case and bolt pattern. But it is possible they used an engine/tranny adapter.

You can bolt an actual GM tranny to an AMC engine with the proper adapters:
Adapting AMC I6 & V8 Engines to GM Automatic Transmissions

Remember that this only bolts the AMC engine to the GM tranny from a 4wd GM as a 2wd transmission from a Camarrow, etc... requires even more work. Even starting with a GM 4wd transmission you would then need to have the appropriate GM transfer case or further adapt the GM transmission to your original jeep transfer case. The possibilities are numerous. The same is true with a factory Jeep TH400: if it was not originally attached to the transfer case you intend to use you will probably have to adapt/modify it to fit your transfer case. The TH400 units from quadratracs will only fit the '76-'79 quadratrac and the one from a Dana 20 jeep will only fit a Dana 20 ( super rare 1980 IH-only D300 excepted) without such adapters/modifications.

You can get a '80-newer AMC-patterned 727 transmission from a FSJ that will bolt to a 304 and to the Dana 300 you list in your vehicle description. You can also get the auto that was actually installed from the factory in a 1980 CJ7: the AMC-patterned 904 (not recommended for V8's) or 999 that will work with a D300

Keep in mind that if you have a TH400/D300 in your 1980 CJ the tranny has been swapped in and has had to been adapted and/or modified to fit that D300 as there was no th400/d300 factory combo! The transmission may also have been adapted to your 304. Do you know what the original application of your parts are, or know how the components were made to work together?
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