hopefully a non biased opinion Transit vs sprinter

[Herbie]

how do you tell what diff ratio is in a transit? RPO code? tag on the diff?

If you have the vin, you may also be able to use an online decoder. I know this works for Sprinters and a few other models, at least. If it were a GM product, I'd say to check the door-jamb sticker for RPO codea, but I'm not a Ford owner, so I don't know where to tell you to look.