Hope you guys can help.

[AM JEEP]

I own a '78 J10 360, TH400, QT, with J20 QT axles. I would like to change my QT t-case with a NP203/NP205 doubler. I have the NP203 that was bolted up to a TH350 and I need the stock adaptor to go from the TH400 to the NP203. my question(s) is the bolt pattern for the adaptor TH350 to NP203 the same as the TH400 attachment point? Also with the output shaft for the tranny, I know I need to replace the foot long 10 spline QT output shaft for a chevy 32 slpine, but do I need to change any bearings or anything?

[Crazy_Jeepman]

The TH400 has 6 bolts that bolt to the adaptor, the TH350 is 4, so the TH350 to NP203 adaptor will not work for a TH400 to NP203. Not only will you have to change the output shaft on the TH400 for a 32 spline of correct length, you will also need to swap the input of the NP203 since it is not correct for the TH400. Since you are completly taking the TH400 apart to swap the tail shaft, might as well put a rebuild kit in it.

[AM JEEP]

I was reading online that you can just change the output of the TH400 to mate up to the NP203, which would be a 27 spline. Anymore info would be great thanks.

[gsmikie]

the output shaft you are talking about came in 83/85 chev diesel trucks it was a th375 output shaft or you could send yout output shaft to ed moser and have it re-splined and shortend it would be cheaper and quicker to have your shaft reworked

[Marvin-fsj]

just got done doing it AA sells and adapter to change the turbo 400 to look like a turbo 350 on the output side of the tranny. if you look around it can be bought for about 350 dollars. high but it works. the biggest tranny shop in oklahoma said the short output shafts for the turbo 400 are really hard to find.

[Marvin-fsj]

oh ya it wont fit without moving the gas tank