Sorry, I was in a hurry earlier(about to head for the track) & for got, his website is at:
www.thard.co.uk . That should give you a LOT of good stuff to read up on(it may mostly be for the 416, but there's still a LOT that works for all Tamiyas, I believe the diff building part is in the TRF416 - Things to know - Updated Mar'09 thread under the title Uber Diff......
