...which all adds up to one more reason to get a newer MB diesel with the OM60x engine! Those all have a nice, simple serpentine belt setup. Piece of cake to work on and zero adjustments. The tensioner assembly has a relatively short life span but that is, IMO, a highly acceptable compromise compared to loosening the AC and PS systems so you can fiddle with the alt/WP belts! I replaced all 4 on my W123 and hope to sell the car before I have to touch any of them again (ugh!)