Buy a box buy the tailshaft. Thats the rule.
Early had a coarse spline. Later ones, 84 on or so had a fine spline with the same rear seal diameter.
Then later again had the more common sized slip yolk. That continued thru the 2.6L motor and the MUA box. I cant comment on what came with it in the USA but here it was the Trimatic (TH200) the TH700R a host of aussie made 4 speeds, similar to muncie and saginaw. The T5 box and the isuzu 4 speed auto.
Cheers, Bob.
_________________
Current project, 1979 KB Isuzu Ute.
Daily driver, '86 Rodeo Spacecab.
Chasing parts for Isuzu Impulse.