Kc;

That's the prefilter. If you didn't hole it when extracting it, you should just clean it by blasting it with carb cleaner and reinstall it...but only after cleaning out the tank of all the rust in there and sealing it...use one of the commercial epoxy kits...but only after a good internal cleanup with about a gallon of traprock poured into the sender hole, then strapped (for instance) to a cemet mixer for rotation for an hour should prep it well for an epoxy inside coating job. Mask off the pickup tube to prevent clogging it. Good Luck

Cheers