Hank! Where the heck have you been? Many Moons is right.

Yes, m35 spiders first to go, fix that, then pop them again, then do a cheesy locker, pop a shaft, then get super m35 kit, then spin or bend housing, then wish you had not spent so much time and money fooling with a m35 and just done a d44 or 8.8 conversion.

Only tj 44s bolt into tjs, unless you buy the RE bracket kit and have them welded on via jig and pro welder.

I could not tell you if a ZJ axle is a straight swap, but a xj axle is close. When going from low to high pinion, the driveshaft most likely will need to be shortened. Also hubs, calipers and inner knuckles are the same on 97 and newer xj 30s, but 96 and older have slight (hair loss causing differences).
Just for the hassles alone, I'd suggest spending the money for having your d30 regeared instead of the wrecking yard route.

If you see a tj 44 in a yard you should buy it, just because they are NOT easy to find. Up to $1200 is normal

If you want a custom 8.8, 44 or d60 built for TJ, I can do that and ship it to you.

SD
Josh