Henry, A 69 Camaro tank will fit your 69 Firebird. It would depend how bad your original tank is whether I would replace it or not. If its all beat up or rusted through I would replace it. Jim
I would take out the old one and remove the sending unit. With the cap off and a flashlight you can see what the inside of the tank looks like. A couple companies like the one that makes POR-15 sell tank sealers. If the outside of the tank looks good (no dents, rust, etc. ) you can paint it, put in a new sending unit and you'll be good to go.