And yet the 64 and older had a pumpkin with an Eaton Suregrip, same as the Eaton suregrip in the 8.75. All the inside guts are the same size and most are interchangeable except there is a different spline count for the side gears for the Chevy axles. And yes I do know this for a fact. And yes Chevy called it a posi traction. Olds and Buick had a bigger version of it. Kim