Good point! Steerfromtherear I wasn't trying to differentiate from a locking diff and welded one, but re-reading my post it looks as if I was trying to

the two achieve the same result, one costs more than the other and will probably last longer.
I have an auto locking diff on my A3 which is a slightly different animal (FWD anyway though

). I wonder though if you can get a switchable diff? Any one got a clue on this?