[HO455]

The different names are a result of the branding by the different manufacturers for a clutch style limited slip differential (LSD). So a Power lock and a Positraction LSD are both the same thing but for different axle brands. And adding to the confusion a Dana 44 in a GMC had a Power Lock but a Dana 44 in Chrysler had a Sure Grip.
Even among the various GM brands there were different names for the same limited slip units. Pontiac called theirs Safety-T-Trac, where Chevrolet called it Positraction, and Oldsmobile named theirs Anti Spin.
Then throw in 10 bolts that have cone style LSD and 12 bolts that are a clutch style, and depending on which piece of factory literature you refer to both styles may or may not have the same name. No wonder it can be confusing.
And all that was before the aftermarket got involved. Whew!
The link has more information.

https://en.m.wikipedia.org/wiki/Limi...p_differential