HELP! TH400 out 700R4 in


Junior Member
" The Money Pit" an '82 chev 6.2 diesel 4X4 1/2 ton with bad TH400 and transfer case .

I have a rebuilt TH700R4 and transfer out of a '89 4X4 350cid Surburan for a replacement.
(1) Are there any major problems I should know about?

(2) Will I need to shorten/lengthen drive lines?

(3) Which tork conveter do I use? the 400 or the 700? Or ???

(4)There is a 4way electical plug on the 700R4 trans. I don't know if the '82 has one. if the '82 does not have one, what next?

(5) Will the shifter for the transfer C work?

(6) There is not a lot room on the trans hump for a shifter. Do you have a clue as to mounting a B&M Mega shifter? Or any suggestions at all.


Junior Member
central NY state
1) The 700R4 isn't nearly as strong as the 400, but shouldn't be a problem unless you work the truck really hard.
2)Yes, the 700 is longer than the 400, so you will need to shorten the rear driveline and lengthen the front, or possibly swap in shafts from a truck originally equipped with a 700.
3)You'll have to use a converter from a 700 that came off of a diesel truck. Diesels have different stall rpm converters than gas equipped trucks.
4)The plug is for the lock-up feature on the torque converter. You can not use it, without any problems.
Also, if you don't already have one, install a transmission cooler-heat is the #1 enemy of auto transmissions. It would be a good idea to drop in to a local transmission shop and pick their brains. If they're nice, you ask nicely, and you catch them when they're not busy, they'll likely have a lot of good info for you.
Good luck.

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