Transfer Case Identification for 1987-2006 Jeep Vehicles

The New Process transfer cases used in late model Jeeps are always a left-hand drop configuration.  The stock rotation on the New Process transfer case depends on the year of the vehicle and the stock transmission used. The rotations are approximately 13 or 23 degrees. The input shaft spline on these transfer cases will be either 21 or 23 splines.  Each input shaft for these 2 counts is a different length.  The factory transmission and engine size used in the vehicle will determine the spline count of the transfer case used. There are numerous styles of New Process transfer cases, and you must be very careful in making your identification of such. The first units were the NP207s, and they were used in the early model Cherokee Jeeps. The full size Jeep trucks and Grand Wagoneers used the NP208. Jeep soon added the NP231 which replaced the Model 207 in 1987. A Model NP242 was also added for the full time 4WD models.

With all of the variations in model numbers, the only variation concerning transmission adaption is the spline count of the transfer case input spline. As previously mentioned, the New Process transfer case has two spline counts and each input shaft is a different length. Both the NP207 and NP231 transfer cases were available with these two different input shafts. The input shafts of the transfer case can be changed if necessary, but this would require that the transfer case be completely disassembled.

The easiest way to identify the transfer case input is by identifying the stock transmission that Jeep used. The 21 and 23 splined output shafts vary on different transmission models. The AX15 transmission is always 23 spline shaft and extends 1/2" beyond the face of the transmission. The Torqueflite and NV3550 are generally a flush 23 spline shaft. The AX4 & AX5 will always have a 21 splined shaft and it is flush with the back of the transmission adapter until 1996. In 1997, the AX5 output shaft was lengthened 1/2” past the tail housing adapter. The Peugeot transmission is always a 21 splined shaft and extends 1/2" past the back of the transmission adapter housing. The AW4 automatic transmission comes with both the 21 and 23 splined shafts.