Ford was forced by the NHTSA to cancel the Uni mid model year 1963, because of safety concerns.

When the frames flexed, the doors could...and did pop open. People actually fell out of the cabs when this occured.

4WD was not available in Uni's.

The Ranger was introduced for model year 1965, which began in September 1964.

Rangers were not available with 4WD until 1973.

IF the seller claims all this jazz, did he/she provide the provenance in the ad?

The provenance = proof = would consist of the VIN and codes on the Warranty Plate.

Without a provenance, this is BS = CACA del TORO!
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btw: There's a supposed 1964 F100 Ranger in Riverside, CA. It's a FAKE!

This truck was at the 2008 Western Nats held in Yorba Linda CA. Don (camperspecial65) and I spent an hour looking it over.

It's a 1964 F100 Custom Cab, NOT a Ranger. The hood side "Ranger" emblems were made up from mylar, the bucket seats have a non Ford upholstery pattern, and...in fact...aren't even from any Ford. They appear to be seats from a late 1950's British MG-A. It has a molded plastic headliner.

After speaking with the owner, he admitted making it up. Then after we walked away, he told the owner (Karl) of the truck parked next to his...that his "Ranger" had the "Galaxie option."

More BS! Karl laughed in his face, because he knew there was no such thing as a Galaxie option for any truck.

Karl has been in this hobby almost as long as I have, has owned dozens of Galaxies and trucks, is a Ford historian and has been the SoCal Galaxie Club treasurer for many years.