A few questions

Will a NP242 with full/part time from a 93 zj work on my 87 XJ?. Im thinking about gettin a parts xj for axles and such what years have the same floor pans as my 87 xj??. Is the 5.2/5.9L zj alt the same as the 4.0L zj alt??. Anything else I can use off a 5.2/5.9L for upgrades on my renix 4.0L?. more ?? to come when I think of them

Yes. It should.

http://jeephorizons.com/tech/tcase.html

No. Wrong spline count. Your 87 is 21 spline. 93 would be 23.