7 1/4 Sure Grip 3.90 Rear Axle

With the Sure-grip in it, makes it much much stronger than the std open diff 7 1/4 rear end.

That's what fails ln the 7 1/4s is the light duty weak open diff and the cross pin working loose in the diff housing.
Yes sir. This one is the Dana Powerlock with the 4 pinion spider gear assembly.