It is, but that illustration is not for the 123.133 (like my 85 turbo diesel) If I look for a 123.130 USA version, it shows both types. Big difference in price for alternator lower bracket! Maybe that is when they went to double belts (bigger alternator?)

https://nemigaparts.com/cat_spares/epc/mercedes/1/m/617912/67k/15/105/?chasis=12313068K

By the way, I lost access to MBUSA EPC. The nemigaparts site is a very useful replacement!

https://nemigaparts.com/cat_spares/epc/mercedes

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5