To my best knowledge, "factory" sunroofs were never installed in Rangers; however they were factory-installed options in the Bronco II.
I was an installer all during the early Ranger period, worked several Ford dealerships, and don't recall ever seeing a genuine factory-installed Ranger sunroof. I did add aftermarket sunroofs to many an early Ranger myself (double steel roof = bitch of a job).
Without looking at every one them, I think that none of my Ford sevice manuals (I got them all, 1984 to 1994) contain any reference for a sunroof in the Ranger model; only for the Bronco II, and then the Explorer. Same story with the sales brochures- not offered from the factory for Ranger; was offered for Bronco II and Explorer.
Ranger sunroofs weren't installed at the factory, but instead were aftermarket items, some being dealership-installed into a brand-new truck.
Here's two Ford accessory catalogs.
1984 Ford accessories; factory sunroof in the B2. Besides the roof, note mention of the "flip-open / removeable quarter windows which will be available later in the model year". The sunroof exists; the quarter windows never made it to production. This factory roof is common in Eddie Bauer packages.
1990 Ford accessories; dealer-added sunroof, listed for Ranger, Bronco II and Aerostar (although the picture itself looks to be a full-size Bronco roof). It's obviously an aftermarket sunroof.
Hope this helps; it's my best knowledge, and recollection, regarding sunroof-equipped Rangers, both from factory literature I have, and from actually being there "back in the day".