Our Advance Adapter 50-6401 will allow you to adapt a GM TH400 3 speed automatic transmission to the Jeep NP231 transfer case. The adapter housing is 1.250” in length and is manufactured from 356-T6 heat treated aluminum alloy. We also supply a mounting provision on the bottom of the housing to bolt-on our heavy duty transmission mount (716008). The adapter kit includes an adapter housing, new 23 spline TH400 output shaft, NP231 input gear for either the 87-94 or 95 and later transfer case, gaskets, seal, fastening hardware, and adapter instructions.
The adapter assembly will fit the Jeep NP231 transfer case with a 21 spline case by upgrading your transfer case to a 23 spline unit. We have included a new input gear for the NP231 with 23 splines to fit the early and late model transfer cases.
The Advance Adapter kit is not designed to fit Jeep New Process 207.
This adapter kit is designed for exclusive use with the GM TH400 automatic.
Back in 1991 my 1988 Jeep Wrangler had a 4.2 AMC engine and a Peugeot 5 speed, which twisted the main shaft spline, . I bought a junk yard Jeep Quadratic GM Turbo 400 for $100 and had it rebuilt with this kit to match the NP 231. It work so good I didn't need to change the drive shaft length. original length 23.5 new 24.5 length, and still works today