need help with a 90 pathfinder/trans. or transfer case

[TnT=rgis]

i have a 90 pathfinder xe v6 auto 4x4. it started making a noise that sounds like it is coming from the transfer case or transmision. i was on the highway and let of the gas to exit. when i did it started to whine like worn or dry gears or bearings. it continued to do that for a few days then it suddenly change to a cluncking sound. it clearly sounds like metal to metal now,like a bad universial but they are good. so i assume it is the bearings in the case or tail of the trans. dose anyone know what items are the first to fail/what to look for? and will a 4cyl 5spd picup trans mission and or transfer case swap in??? i have access to these parts cheap. just wanted to know if they will work with the addition of a v6 bellhousing or not???

[Desert Rat]

I think you can tear down both cases and replace the 4 banger input with the V6 one. The difference is 24 vs 30 splines, but everything else in the Tcases is the same.