Catalina 350 International Association

HELP! Our fill cap for the fill hose for deisel was deep-sixed by an idiot fuel-dock employee. I rushed out to my local west-marine and bought a "standard" fill cap to replace it but it didn't fit (it was too big)! Now I don't know what size the 350 (original mark-I, 2003) is using and where to get one since West Marine didn't offer any other sizes. I tried searching online but didn't find any that were smaller than the 1.5" size that I already tried. Anyone know what size I need and where to get one? I'm in a hurry because it's raining and I don't want to get water in the tank. Currently have duct-tape over the fill, but not sure how long that will last...

(also, not sure if this should be under plumbing or engine, so will post in both locations...)

I would try warren pandy at catalina yachts in Florida -parts department. He is helpful and should have the part or be able to direct.you to the right place. I don't have their phone number handy