I'm pretty sure if you have the newer type system you will have to enlarge the hole or drop the tank. (not fun I did it) I enlarged the hole while the tank was out and made a new cover and installed it with nutplates and stainless hardware.

Jim

"Every normal man must be tempted at times to spit upon his hands, hoist the black flag, and begin slitting throats".--H.L. Mencken Bumper sticker, OXYMORON #65 - Liberal Thinker