Asin-Warner AX15: 5-speed in 90-00 4.0l I-6cyl and 2.5l I-4 models. Earlier versions use an internal slave cylinder, which changed to an external slave cylinder sometime in the mid 90s. 23-spline output shaft. 3.07:1 axle gear ratio.
Gear ratios: (1) 3.83:1 (2) 2.33:1 (3) 1.44:1 (4) 1:1 (5) 0.79:1 (R) 4.22:1
His Jeep should have the AX-15, not the AX-5.If it's original,that is.
Ax-15=23 spline.
AX-5=21 spline.
New Process NP231 Command Trac: 2-speed, chain drive, part-time 4WD. 2.72:1 low-range. 87-01 2.5l 4cyl and 4.0l I-6 models with manual or automatic transmission. 87-89 21-spline input, 90-01 23-spline input. The older models used a vacuum switch to activate the dash indicator lamp and engage the front axle disconnect. Newer (non-disconnect axle) versions used an electrical switch to activate the dash lamp. The shift indicator pattern is 2WD > 4WD high range part-time > Neutral > 4WD low range part-time.
As far as the transfer cases go,ALL 90 up is 23 spline no matter what combination it was mated to.
And CaliGold, please don't think I am trying to argue with you.I'm just going by what the sticky says