Auto body repair & detailing: rust, rear quarter panels, steel experience

Question
i have a 83 buick that i parked with a strong body that sat for a couple of years now i found some rust in the bottom of both rear quarter panels about the size of half dollars on the outside is just discoloration of the paint but on the inside its flakey and soft on the outside and i don't have the steel experience to cut out and replace but i'm excellent with fiber class. will it hold if i cut out and replace with fiberglass?

Answer
Nope. Fiberglass has no place on the steel body of a car. You can glue steel patches in with structural bonding adhesive, that will last pretty well- the trick is to properly clamp the patches on. and hold them on the face with screws or rivets untill they dry. Once dry, remove the rivets, and apply more glue over the holes left by the fasteners. Some structural adhesives require special body filler, ask the parts counter person who sells it to you if it does. If he don't know, research the product online. SEM adhesive definitely does, Kent products do not. Bill