EHHH … 90-91 are the same B series transmissions… 92-93 are still cable trans. but use the same main shaft as all the 94+ B series hydro’s transmissions. So if you are switching from B16 to B18 a/b whatever it will work fine… you are keeping the same transmission and thats what really would change things. The B series blocks basicly have been the same really since 1989 or so.
Good luck anymore Q’s just ask.