Originally Posted by Tang87
The np231 came with a 21 spine input from a Cherokee and a 23 for a wrangler. The Cherokee and newer np231 from tjs?? don't have through vacuum port for the front axle....
the 2.5L came with the 21 spline, and the 6 cylinders (AX15 and BA10) came with 23 spline. Cherokees are the same way.
My 90 YJ with 2.5L has the 21 spline, When I bought a replacment tcase from a 93 with the AX15, I was forced to replace the input shaft it had a 23 spline.
I want my old tcase repaired, the one I bought has a blown out set of low gears (just found out last week) so im pushing the wife (read "butt kissing") for her to slow down on groceries so I can get the JB ultra short SYE, shaft and electric speedo....
Should be a $700 ish repair with my labor.
450920 Diff Cable Lock Kit Jeep Wrangler YJ 3-6" | eBay
should fix your vacuum issues for the front axle.