Spicer trac lok

Trac loc has a single pin with 2 spider gears.
Power loc has 2 pins with 4 spider gears. Stronger can handle more abuse.
Both are rebuildable.
I've never seen a power loc in a 9 1/4.
My wifes 78 Little red express has a 9 1/4 sure grip that uses the cones instead of clutches.
Dana owns Spicer and Eaton axle and brakes.