Aragon,
If you need some demensions on the 51T spur gear let me know. What you should see in the pics below, is a Hyper 7 center diff, with a 51T Ultra MBX spur gear. The adaptor you see there is from JT Racing. The adaptor was originally ment for the 62T dominator Steel gear, but the 51T delrin spur from the ultra series buggies fits just fine. Someone should suggest to Mike to order 20 to 30 pieces, bet they will sell on his website.