The rear bumper was an option, even on 1/2 tons, up to the early '80's. It's not unusual to see dealer installed aftermarket bumpers on older trucks. The AD rear bumper is much flatter than the front, I've only seen 1 1ton with a rear bumper. Even most TF trucks I've seen don't have factory rear bumpers. That's 1 option mine actually had, along with turn signals and the 8 leaf spring option.
