The GM TH400 main shaft kit is used when replacing a 700R4 in GM full size truck applications using the NP208 / 241 series transfer cases. Once installed into the TH400, the output side of the TH400 looks identical to a 4WD 700R4 that is being replaced. The adapter kit includes adapter casting, new TH400 output shaft, adapter plate, TH400 gasket, o-ring, and adapter instructions.
The GM NP 208 / 241 transfer cases are chain driven units with a cast aluminum case. When originally coupled to the 700R / 4L60 / 4L60E the NP208 / 241 featured a 27 spline female input shaft, and were used in GM full size truck line-up in models years 1981-2000.
This adapter kit is designed for exclusive use with the 4WD GM TH400 automatic transmission. The TH400 has a case length of 24.250” and a “Texas-shaped” oil pan underneath it. The factory output shaft has a spline count of 32 spline and had various output stick-out lengths.
Note: Our adapter kit includes a new TH400 output shaft that must be installed into the transmission.