The 8 1/4 thread

Just to jump in here.

I believe there were two different case sizes for the 8.25. If you want gears that are 3.21 or numerically bigger, you would have to find a rear end that already has a 3.21 gear in it. Not that its hard to find, but adds another thing you have too keep in mind when looking for a 8.25

but I am with what the others have said, keep the 8.75 and get new axles.