[Batfish]

Looks like the MBX - good news :) It uses the diff that accepts plastic spurs with no modification.
First, get the nylon/plastic spur that Mike sells here (51T). Then get a couple small pinions to work with.
Next, it's time to start hacking away all the stuff that's in the way of electronics. Maybe figure out a way to get the steering servo out of the way, too.
I have a buggy just like it that will be a winter project for me. I'll have about 6 months+ to get it ready for next year, so I'm in no rush to start.
My current plan is to run 4s2p lipo with an MGM 12012 and Feigao 8L. I may end up with a different motor, but we'll see. I'm building it to compete with nitro next season. One thing I plan on doing is putting my center diff on it's side (similar to the way I did my MGT) and raising it a little to use the OFNA 65T nylon spur. Lastly, I'd like to end up using Gorilla Maxx battery straps to hold down the lipo packs, so they'll most likely end up over the rock guards on both sides.
Considering I'm not working on mine for about a month or so, I'll expect you to get ahead of me ;)
We can learn off of each other on this project.

Best of luck, of course - and I'll go check mine out again to start getting some more ideas for you.

:)