belt bearings

Hi all I've just changed the bearing on the tensioner on the alternator belt now the tensioner bearing on the air con belt has started the sing to me. Are the two bearings the same or a different size?
Its a 1998 300tdi
Thank you.

The bearings that are replaceable can be removed and the bearing number will be on them. If the whole assembly (bearing and pulley) has to be changed then you cannot get the bearing out in the first place.

Disco 2 V8's are all I have details for so not a lot of help to you, but if you look closely at the idler pulley you'll soon see what you can replace or not.

Peter