I've posted this a couple of times before in response to this claim, but I'll say it again...I've been running a remanufactured steering gearbox that was sold for a 1984 E-350 van in my truck for almost 11 years now. The previous owner of my old van bought the gearbox to replace the gearbox in the van and never got around to installing it before selling the van to me. He gave me the gearbox, still in the parts store packaging, when he sold me the van, and I decided the original gearbox was in good enough shape to not warrant replacing it. I kept the gearbox when I sold the van in 2002, and in 2005, I swapped that gearbox into my '84 F-250 4x4 pickup. It was exactly the same part number, fit exactly the same, and certainly does not go backwards. I do question the quality of the rebuild; there's still way too much looseness in the gearbox, but it does fit and function the same way a truck gearbox will
I did a bit of research to back up my experience in case you don't find that acceptable, and I will give you this much; it looks like 1980-1982 vans used a different gearbox that is not compatible ('82 appears to be a changeover year; both the early and late gearboxes are said to fit '82 vans)...however, '83-'96 vans DO use the same gearbox as the '80-'96 pickups do, per cross-referencing on AutoZone, Napa, and RockAuto.
Screen-shot of RockAuto's cross-reference guide for the Motorcraft remanufacturered gearbox:
You must be registered for see images attach
