I did the swap, very happy with the hearing. Must say though, everything I've read says it's a simple swap...Not! Maybe the 510 3rd member is the same, but the 720 case is larger inside to account for larger spider gears. I had to make shims out of brass to back the splined gears, 180 thousandths each side. But with that they fit nicely, no slop and smooth running. If you have the ability to make these shims, I recommend this swap.