Hi, Dan,
I've wanted to do the same thing on my NP242 but I don't have the funds right now. From what I've read you have two general options: 1. Buy a complete SYE kit which will include a shorter output shaft and a new output housing, then completely rebuild your T/C, or 2. Buy a "hack and tap" kit in which you will cut off some of your output shaft (while in the vehicle), tap the end of the shaft for a bolt, then bolt on either a flat flange (Rubicon Express) or a yoke (Iron Rock Offroad). With either method you will then need to purchase a new custom longer driveshaft which will have the slip feature at the rear differential end.
Good luck.
Jay