I think this should drop right in, it is for an Ofna ravager:

http://www3.towerhobbies.com/cgi-bin...?&I=LXHWB6&P=Z

Here is why I believe it will also fit the mutilator: I have both a mutilator and a ravager. I just cross checked the part numbers for the center diff assembly and both share the same center diff plate (40041), center diff mount (40040), and center diff assembly (internal gears, diff case, brake cap joints). The diff mount posts are different (longer) to raise it up on the mutilator because of the bigger spur gear.

I don't see why it wouldn't work.