Screw that, good things come of mixing compatible components. the xterra tranny is an upgrade to a pathy. the 3.3 is also an upgrade. the older tx-10's with wider chains are good to hold on to as well.
Wasn't made for it... PHHH! It was made and the car MFGR decided what it went in. You you can deicide what it goes in next. Just need to do homework thats all.
Hell I got an import tranny that came of a 3.3 nissan and it came with an electronic t-case and my old tx-10 bolted right to it.
The best of all that has come from mixing and matching is the VG34 and NISSAN mixed and matched that one first;
VG33e, VG30DE rods, VG30e W-series heads, Q45 pistons, VG30et oil pump, Nisimo #2 cams...
^ Parts from 5 different engines, the King of mix and match right there and it came out to be an awesome little torque monster for BAJA racing.