1998 Chevy Tahoe Fuel leak on Fuel tank

Yes it could be. But, the welded seam around the tank often rots out. The only way to tell is to drop the tank. The bad news is this -- 98 Tahoe fuel tanks are not available from any aftermarket maker ( as far as I know). You must buy one from the dealer. For some reason the 98 tanks are unique to that year only. They cost around $500 bucks. If replacing the tank, I do suggest installing a new fuel pump assembly $250 and a new gasoline filler hose $130 and most importantly a new fuel pump wiring harness connector. If you unplug the fuel pump you MUST replace the harness connector every time -- failing to do so will cause serious problems. Also, make sure you recrimp and clean up the fuel pump ground where it connects to the frame cross member -- just before the fuel tank.