Before the Suregrip, for just a few years Mopar used the Dana Power Lock as a positraction differential. Its manner of operation is different from the Suregrip's. I found an NOS 8-3/4" 3.73 Power Lock just by accident and put it in my Valiant. So since technically Mopar used more than one kind of positraction diff, maybe it is correct to refer to them generally and not just as Suregrip.
