Kato
Having grown up in central Cally in the 60's & 70's, I have seen many 50's to mid 60's trucks with that type of bumper. In fact it seems that it was the norm to have one on the rear of your truck. Don't know where this name came from--but we always called them 'Barden' bumpers. Many trucks appear to have been sold, new with out rear bumpers, thus the dealerships sold many Barden bumpers as add on's. They are heavy duty & worked well----if they weren't so ugly compared to factory bumpers.
delky dave in WYO