transmission on 1984 nissan pickup (diesel converted)

[cierva]

i have a 1984 small nissan pick up- 2wd. 5 speed manual. it was converted to diesel a while ago, it now has a Nissan Diesel s22 engine. Now, i have a transmission problem... is there any reason to think that the trany was changed as well, or are they compatible?im looking at swaping it out myself, but i'm not sure if i need to look for the same type that would have come originally with the truck and the regular gas engine, from other same vintage nissans. any advice?