Spare belt part number

[wanderer44]

I have a 2019 dynamax isata 3 24fw. I want to carry a spare serpentine belt. It is hard to see under there so I am not sure that there is only 1 belt there driving everything. I have asked at several dealers and they can not come up with a belt number for the Mercedes 3.0 v6 engine. I have looked up a lot of them and having trouble understanding the several different belt lengths.
I would sure appreciate if someone has a good number they could give.

Seems like not all parts books are up to 2019 listings too! thank you leoonard

[Iwannacamp]

I would bump the starter till you can see the number(may have to get under). Get some Fantastic type cleaner and a cotton rag. You will be surprised when you clean it. I sold belts for 25 years. They are nearly always legible.