Volkswagen: A4 Quattro differential bearing, salvage yard, input shaft

Question
Hi John.  I am also an Allexperts volunteer, so I appreciate the help you provide to others.  Here's my question:  I recently took my 1998 A4 Quattro 2.8l into a mechanic for a rear wheel noise.  Turns out the differential bearing is shot.  He is recommending I replace the entire differential with a low mileage used one b/c he says it will be cheaper due to lower labor costs of replacing the entire thing vs ripping the current one apart and replacing the bearing.  Any thoughts on this?  He found a low mileage used one at a salvage yard w/ a 2 year warranty  for $1200 and wants to charge $550 for labor to replace.  Thanks for your assistance.

Answer
when splitting the rear diff, the input shaft has to be withdrawn which is located into a sleeve (which usually falls out and causes countless problems when rebuilding). the diff bearings are difficult to replace, and take a while to set up the correct amount of free play in the diff using shims. so i would agree that the replacing it with a second hand diff is going to be cheaper and quicker. i would have thought that you could get one alot cheaper than that though. the last one i replaced cost £250 for a low mileage used one. Also, you only get a 1 year warranty on a brand new one from audi, so a two year warranty is good, however they are not common for going wrong, so that is debatable as to whether it is worth paying more for a longer warranty. the job should take around 4 to 5 hours maximum to carry out.