A tundra diff could be put in a mini housing. The depth from the mounting flange to were the axles go into the diff is the same on the mini and the tundra-tacoma. It would be a matter of filling, drilling, and tapping the new bolt pattern. You would also have to push out the back of the housing to make room for the braces. A diamond would be easier but if you had time you could do it much cheaper.