When we were kids my dad had an RV shop. We minions were his work force and wired up all the tow vehicles to campers and trailers. The early 70's Ford pickups that were "Camper Special" had a factory camper plug under the front drivers side corner of the bed. The bracket that held the recptical almost always had a pair of Vise-Grips holding the nut in place so the guy/gal on the assembly line could air gun the bolt. They seldom took the Vise Grip off. It was good supplier of Vise Grips. It the later years when a F250 or F350 Camper Special came into the shop we'd find a rusty pair of Vise Grips still there!