More things to consider than just the differential.

Does your 94 have the factory tow & payload package option????

If not, with that much boat behind your Ranger, you'll likely want to consider adding at least that & maybe a cushioned ball mount & class-3 frame mounted hitch & seeing as how we have to Stop what we tow, maybe consider a brake upgrade too.

If your gonna have to do all that, maybe just trade the Ranger for a F-150????

More thoughts for pondering.