I'm assuming you have the AX5 right now, and your wanting to swap in the AX15? The AX5 is a very weak tranny.

The AX5 has a 14 spline input shaft.
The AX15 has a 10 spline input shaft.

The AX5 has a 21 spline output shaft for connecting to the transfer case input shaft.
The AX15 has a 23 spline output shaft for connecting to the transfer case input shaft.

Additionaly the bellhousing paterns are close, but not close enough. So in a nutshell, no they won't interchange. Sorry

no the spline counts on the input are off.  and the bellhousing bolt pattern is off.  i have heard though that the ax series trannys have removable bellhousings though so in that case i'd assume you could swap bellhousings.  then get a 23 spline t-case or alternatively a 23 spline input shaft for your current t-case and swap it in. 

basically as adam said its not easy or a garenteed swap.