Mine was TDI'd a while ago although the rebuild is ongoing, was a TD now sports a defender TDI, using the tdi sender, stat works fine and it reads just out of the cold area when sat idling for as long as i want and 1/3 of the way up if worked, if anything TD always registered hotter, change of rad in the offing as the tdi one i have has no fins left :) AT ALL!!!, will see what happens then.
Cheers Steve