hi mate, just read up the full thread,
i bought a mad monkey not long ago and when i first ran it, it went 3 metres and let off the magic smoke, so i tried the slipper clutch and all was well, now then i checked the diff and thats where the trouble was.
firstly lift up the rear end and spin the wheels, if it feels rough or stiff its far too tight, take out the driveshaft and loosen it to the point where you can turn the wheels with a finger laid accross the tyre. build up and try that.
i put a ezrun 8.5t in mine and it went like stink!!! 10.5t will work fine as would the 9t, its only 2wd and my mate (heavyleftthumb) runs one in a slash and has done for the past year and its mental!!!