I think it's likely cuz the GM brass were cheap screws, trying to save a buck to keep the truck cost and price down - the same era cars had locks on both front doors, and other makes of trucks had'em on both doors, so it wasn't "industry standard"
Bill
Not so. Other makes of trucks are set up the same way. I have several Internationals and a couple F@#ds, and they're all like that--only keyed on the passenger side. And one of them is as new as 1959.
