The Doner t-case is my original 1990 242tcase. I blew it up 2 years ago, and we put a 231 T case in. Now when I put it in 4-wheel drive there's a lot of popping noise coming from that t-case so I got a 242 case from a 96 ZJ. The ZJ case is 23 spline but my original 242 is a 21 spline. I was hoping that I would be able to pop them both open and just change the input shaft to get back running.