Save yourself some holes
.......................as you now know any upgrade is an improvement!
Just a thought that may save you a few 'holes'.
Try and decide what skid, track and drivers you are going to run and install them all at once.
The first pic is stock drivers, stock track and Polaris X10 skid
The second pic is Wahl 8t extras, X10 Skid with 1" cut of the front of the rails,2" track and 20-39 gearing(skid is only mocked in, and no motor in sled}.
Moral of the story every hole has moved, the holes will be incorperated into the bracing.