What type of posi for Dana 60 diff?

[Ozark Tim]

As some of you may know I am in the process of a resto on a 72 Custom Camper/20. This truck has a Dana 60 with 4:11's and no posi.
First off what did G.M. use if you were to purchase this truck new with positraction? Secondly I am looking for something that has nice characteristics. I do not plan to go to the extreme in any way as the truck is 2wd anyway, but more plan to put a boat in on the ramp at the campsite, or crawl up a gravel road to a remote hunting spot etc. I definately am hoping to find a system that does not chatter, bang and grab. I have had lots of different units in the past and some of them were just plain miserable for the little bit of benefit they gave.
Any suggestions or comments on those who already have something in use?
Thanks, OT