News to me but anythings possible, could have been VW using up extra stock. Shure the truck was actually built for 61?, I've got a late 60 that's been registered as a 62 from day one, maybe it was a dealer truck or demo, don't know.
I do know that VW changed the corners to accomodate the bus bumper in mid 60, what they or a PO bolted on after is anyones guess. There was a time when wrecking yards were infested with those things and a primo bumper off an earlier donor would have been just the ticket before Dad got home and found out you were driving his new truck and bent the bumper