GM TH400 to Jeep NP231 21 Spline Transfer Case Adapter

 

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 21 spline TH400 output shaft, gaskets, seal, fastening hardware, and adapter instructions.

Note: If the NP231 21 spline input measures 2.12” in length from the face of the transfer case, the input shaft must be modified “shortened” to a 1.50” stickout.

 

 

The adapter assembly will fit the Jeep NP231 transfer case with a 21 spline input shaft. This input shaft protrudes from the face of the transfer case 1.19”. Introduced in 1988, the Jeep NP231 is a part-time transfer case became the standard for XJ and YJ models. It was also used in six cylinder ZJ models through 1995. Chain driven with a 2.72:1 low range, it’s reliable even with more than stock horsepower applied.

 

The Advance Adapter kit is designed to fit Jeep New Process 207.

 

 

This adapter kit is designed for exclusive use with the 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.