Swapping 9 inch to 10 inch

I believe the tracks are different.

Nope the tracks are both the same at 55.56, and the perches are also the same,but the flange to flange is different.There's almost 2 extra inches in the 72. I'm assuming that's to allow room for the bigger brakes.
As long as you are swapping the entire rear end, compete, it should be a direct fit.
Alternatively, you could swap the gears from the 63 into the 72, but that requires some expertise.