Found seat tracks from a 1995 standard cab Ranger with a 60/40 seat (the seat was roached, otherwise I'd have just used it). The seat pan/seat side of the mounts is 14" side to side and front to back, so any seat with holes in those locations will fit.
Went looking for Escort seats, because they had a bunch at the yard I found, but they're 16" wide at the mounting holes. Looked at Focuses too. No dice there either. Had just about given up when I walked past a 4th Generation Mustang with the seats already out, but the tracks still in place. 14" square mounting points for the seats. They had a half dozen with seats still in them, but closer inspection showed why they were still there, the seats were all trashed. On the way out with just the tracks and I noticed one more with the Camaros. Tan seats, no tears/holes, but with some grease. Yanked them out and took them home. Now residing in my Ranger.
Looks like we can add these to the list of swapable seats.
Here's the underside of the passenger seat, with one of the tracks installed (I didn't think to take a pic before that, sorry).
You can see there are four available holes to use at the rear of the seat. The already threaded hole is 14" (center to center) from the front mounting hole. They are 14" (center to center) from the other side as well, perfect for a standard cab Ranger. Not sure about extra cabs here, their seat tracks are shorter on the floor side (like the Explorer, but I don't have an exact measurement).
Here's the same seat with both tracks installed, the connecting rod for the slide mechanism attached and both rails all the way back. Notice how one rail is longer than the other.
Driver's side with both rails attached, all the way back.
Mustang seats (wrong color and smudged with grease, Dickies seat covers tomorrow until I can get new uphostery/factory fabric).
As mentioned in the original post, the additional holes needed are there, with plugs in them, but not tapped. The OP suggests that a tap is needed to do this, but that is not the case. Ford doesn't run taps on their assembly line, it would be a waste, they use self-tapping bolts
, which I notices when the light hit the bolts I removed just right. I used an original bench seat bolt as a tap, with a squirt of WD-40 just in case, and it worked like a charm.
Before "tapping" the hole:
Overall I am happy with the results. MUCH more comfortable than the bench. Perhaps a bit of head room, but no real additional leg/arm room though. The seat-backs are as thick as the bench (at least). I'll be looking for other seat options when I go looking for side mirrors and other odds and ends, and will keep everyone posted if I find suitable donors.