I have one
I'm just reading this post today... anyway, my late 66 V8 Bronco wagon has/had the pony interior in parchment, just as shown. Quite rough after many years in the sun, though. Fairly sure it it was factory, but I've always wondered. Mine had an all black rubber floor mat in the front, but it hardened and cracked to bits. Also had the parchment door panels, dash panel (and speedo), and sun visors.
It has solid provenance: it was bought by my father-in-law in 1967 from the original 1966 purchaser and he was pretty sure that it came from Ford (not dealer installed). I have the original window sticker that mentions nothing specific, but does have a "Custom Equipment Package" for $80.57. It also came with chrome bumpers, so I figured they were part of that package, too. Does anyone know more about the contents of that option package?
For better or worse, I have kept the front seats out and have not restored them. I had heard that Bronco front seats were actually Econoline, not Mustang, and have somewhat different padding and upholstery. Can anyone confirm if that is true? I do not want to order Mustang parchment covers and have them not fit. I will probably use the back seat as-is since it is in pretty good shape, but in the long run, it would need to be re-done. I suppose I would have to get the raw material and have a shop custom cut and fit since I doubt it is the same as a Mustang rear seat shape.
I always thought the pony inserts were brown, but reading the earlier comment about green and then looking at my rear seat, I can see it must have been green but turned brown where exposed to the sun.
If folks are interested, I can post pictures of the seats and the window sticker.
Gary