My dad had a '94 Van, but that doesn't make me an expert. I know they basically had the same 318/360 magnum engines. I would think most engine parts would interchange. I'm pretty sure the wheels were the same lug pattern too. Not sure what else would work. But again, I'm just making an educated guess (at least I like to think it's educated ).
Unfortunately not much. The chassis is totally different....the B-van's chassis hadn't changed much since 1971. The drivetrain and rear are probably the only thing that will interchange and that of course depends on what model years we're talking about. After 1984 the B-van and the trucks went to a 5 on 5.5" bolt pattern, so the Ram's wheels will fit a Ram Van and vise versa.