Transfer Case Identification for 1987-2007 Jeep Vehicles

The New Process transfer cases used in late model Jeeps are always a left-hand drop configuration and have the same circular bolt pattern as the Dana 300. One of the differences between the Dana 300 and New Process transfer case is the rotation. 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 splines on these transfer cases vary from 21 to 23 splines, and the transmission that is mated to these transfer cases had either a long or flush output shaft length. It is crucial that you identify the correct spline length and tooth count before ordering any adapters.

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 that we see concerning transmission adaption is the size and tooth count of the transfer case input spline. As mentioned in the second paragraph, the New Process transfer case has two basic spline counts and each spline count has two different lengths. Both the NP207 and NP231 transfer cases were available with these two different input splines. The input splines of the transfer case can be changed if necessary, but the complete transfer case will need disassembly.

The easiest way that we have found to identify the proper transfer case input is by identifying the stock transmission that Jeep used. The 21 and 23 spline output shafts vary on different transmission models. The AX15 transmission is always 23 spline and protrudes 1/2" beyond the face of the transmission. The Torqueflite and NV3550 are normally a flush 23 spline. The AX4 & AX5 always have 21 splines and is flush with the back of the transmission adapter until 1996; and then in 1997, the AX5 output shaft was lengthened to a 1/2” stickout past the tailhousing adapter. The Peugeot transmission is always 21 splines and protrudes 1/2" beyond the back of the transmission adapter housing. We have seen the AW4 automatic transmission in both a long 21 & 23 spline.