Look inside ra2.mix, and local.mix within that. You'll find a whole pile of stuff in there. And the units you were looking for:
Mammoth Tank = 4TNK
Mammoth MkII = HMEC
Titan = MMCH
Wolverine = SMECH
Unfortunately, the cameos either aren't there, or are in the wrong palette. If you're just doing your editing in a map and not through the INIs, you can't change the cameo anyway.
Edit: Hehe, 333rd post. Next target, 666
Mammoth Tank = 4TNK
Mammoth MkII = HMEC
Titan = MMCH
Wolverine = SMECH
Unfortunately, the cameos either aren't there, or are in the wrong palette. If you're just doing your editing in a map and not through the INIs, you can't change the cameo anyway.
Edit: Hehe, 333rd post. Next target, 666