Transfercase problem?

[924x4]

Ok so i was out doing a little 4x4in in my 92 explorer. while stuck. i was spinning in 4Lo and I heard almost like a clunk then a noise whinding down,once i was out i was just trying to figure out, if my 4x4 still works. ( wich it does) now what happens is everytime im in 4x4 and i give it some good gas i get a bit of a clunk, and when i engage into 4lo i can hear it in the transfer case, it engages alot louder. if i stay out of the gas it doesnt make this noise. ive checked my u joints they all seem to be ok, i forgot to check the one closest to the t-case, wich would probably be the one at fault.. i have also changed the fluid in the diff. both auto hubs still look and work fine( i know there garbage to begin with) but im just wondering if anyone knows what it could be. im basically assuming its my t-case, is there rebuild kits available? Thanks again!

oh, and incase this would make a difference its got a 3 inch body lift and 33's