xcase spline count

I did a quick search but didnt come up with what I was looking for. what year xj transfer case had what # splines? and do 231 and 242 have the same # of splines for the same years? and last other that a d300 or an atlas is there any way to convert a 231 or 242 to gear drive instead of chain?

the reason for these questions is that I want something stonger than my 242 but im wheeling on the cheap.

TIA