Chinook RV

Donated my gas cap at a recent fill up. Went to a couple auto parts stores and have tried multiple models and haven't found anything that fits. It's a 98 Concourse on a 97 Ford 350 van chassis. Recall the cap has longish snout with 4 plastic tabs that grab the inside of the filler neck.

I think it is standard Ford E350 cap, right? You need to go to better auto part store, or visit the junk yard.