If you are in need of a replacement or just want a spare you can get a NOS AC Delco cap on Ebay from carb_ologist.
I have ordered 2 from him and they are in perfect condition. Last I looked, he still has 8 in stock.
In my previous searches I found dried or cracked gaskets. Any brand other than AC Delco, including those from The Fiero Store are near impossible to install due to a different metal plate underneath the gasket.
