Re; "I too have installed many Ford Service paper wrapped bumpers. Never encountered any that needed anything more than a shot of Windex, or a quick going over with liquid wax for clean up."
Perhaps there was a date when Ford stopped coating the service replacement bumpers? Mine was shipped to Ford dealer in 1976, I could see at a point/time, perhaps when cars gave up on chrome bumpers or they started using the paper-that-resists-rusting. There's no way on earth that production and service replacement bumpers did not have the stuff in early 70s. It did not matter if it was Ford, Linc-Merc or Ford Trucks.
I get a kick out of the 80 year old dad that said they scratched bumpers getting the crap off, to me it was more like dissolving the stuff rather then scrapping a lacquer like film off. That's why we used 000 0000 steel wool, Afta, liquid wax and lot of what my dad called "elbow grease".