I don't believe any T18 from 1980 on came with the dana 300...I maybe wrong but from what I have read they came
with NP208's. If the t18 is from a 258 model it will bolt in with no input shaft modifications.
'78 CJ7 258 T18/dana 20...dana 30/amc 20 w/ mosers & lockrights...
'glass body w/ tied in full cage...warn x8000i