But draw the diff in with a bearing on the inside - Then rotate around the diff and the bearing will be on the outside...

I think I need to clarify that picture. The small rectangle is the bearing, and the large black polygon is the diff.

EDIT:
Just to further clarify, I have attached two more pictures. The first is an old one of my Hyper 8 and the motor in the right rear position. The second picture is with the motor mount, motor, and diff rotated as I showed in the previous picture, with the motor in the front left.

The bearing won't be on the outside, the diff, diff mount, motor and motor mount all get moved as one object, like MetalMan showed.
A guy at racing has a Kyosho ST-R truggy and another with a ST-RR, both with Mikes motor mounts. Because we slowly shifted from racing e-maxx to racing truggies most of us are using dual battery setups, so they shifted the motor to the front left to make room for batteries. You might have to put a spacer under the diff and motor mount to keep the spur away from the chassis. Or make a cutout for the spur, like it has at the back. They were using the 50T steel spurs and it might not be an issue with the 46t, I'm not sure.
I'm not sure if you can flip it with all cars. For some annoying reason my TTR ST-1 has a different hole spacing on the chassis between the front mount and the back mount.

This is the ST-RR just after it was finished.
http://www.teamadrenaline.net/e107_f...icture_219.jpg
http://www.teamadrenaline.net/e107_f...icture_220.jpg
http://www.teamadrenaline.net/e107_f...icture_221.jpg
http://www.teamadrenaline.net/e107_f...icture_222.jpg
He was going to try and change that aluminum mounting plate a bit. The reason it sticks out so far at the moment is because his BEC and transponder are under there.

Hey MetalMan, I want to see a real version of that dual motor buggy :yes:

In your dreams :lol:.

If I go with Monster Mike's Mugen mount can I still use the Mugen carbon fiber top plate? :neutral: