I have a 300 Tdi and there are two different length belts because the alternator pulley came in two different sizes my local LR dealer installed the wrong one (longer) and I forever had a squeal because the tensioner was down on the its end stop providing very little tension on the belt. As soon as I installed the shorter one a 7PK 1580 for my 53mm pulley the problem was solved. Check which size alternator pulley you have and then check if your belt length is correct. I've just recently replaced my A/C belt and now that squeals for about 10 mins down the road, bugger!
