Look for a key such as this:

https://www.ebay.de/itm/Orginal-Tankdeckel-Mercedes-W123-W124-W115-8-Huf-ohne-Lueftung-B1-/254177528017

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now