86 n/a. 5 speed. swaped into a 87 b series truck.

i was just wondering how many of you guys out there ever work on your transmissions. i have (what i think) are the main bearings in my transmission going out. i get the usual transmission howl in all gears but 4th. it still shifts fine, but i was wondering if any of you have had to replace these. is it relatively simple or would it be easier to just swap out transmissions? i checked out the manual, but sometimes its tough to get a good idea of how much work it really is. anyone know? throw out bearing and clutch are relatively new.