The issue is the center diffs rear bearing. The rc-monster mount has a slight indented lip carved in it like the stock one for the flanged bearing to rest in, Rc product designs mount fits kyosho spurs (but not stock or RRP spurs) it has no lip and it places the center diff in or out (I cant remember) a mm or 2. If mike just didnt make that lip you could use the kyosho spurs, but not the stockers, wont work both ways. Maybe offer 2 mounts ? ( I had both mounts)