I guess it could be something to do with it. Probably would be the transfer mount vs motor mount. If you still have leaf springs, check the tightness of rear ubolts as well, you could get slop there too. If they get real loose you start breaking u joints, yoke, or drive shaft binds. Might be an early sign. Another thing I always check after a good run is tranny/transfer case bolts. They can work their way loose and seperate some. Maybe they were not all put in tight enough after your rebuild.
If it's not any of that, well, then not all rebuilds come out as planned
and hopefully you have a warranty or an extra weekend to look at it.