I put on an MX400 main gear a while back and it has worked pretty well with the Axe's mainshaft. I did have to do a couple of things though to make it work.

I had to press out and flip the one-way bearing so I could center the gear without cutting the frame.

I also had to flip the mainshaft and drill a new hole for the rotorhead bolt. The reason I did this was so the bearing didn't have to ride on the flat spot cut for the Axe's stock main gear.