Where the yellow highlight is there is a black caulk that goes all around where the gas tank sits inside the metal shield. This photo hard to see but wonder what would be good to use to replace. Had to put a new shield on mine so all the caulk came off. Guessing all it does is keep rock and debris from getting inside the metal shield. Any ideas what would be a good replacement? Searching the internet and all they seemed to show was caulk that wouldn’t react with gas but I don’t need that. Just something to keep garbage out of the metal shield.

Silicon

Some form of permatex.

the JB weld brand black rtv
https://www.napaonline.com/en/p/NCB31919

Change the tank is what I would do and not screw with it, if it just a plastic cover with no gas hitting it I’d still not screw with if. Unless it has some real functionality I would not sweat it. If it’s important I’d change the whole tank and cover out.