I got a Rust Problem

[BenU]

above the winshield on the inside there is a lot of rust on every cab that i find around here in the northwest. All the rust forces the seal down and you can see all the rust. On most of the Trucks i can take a screw driver and push it through the metal right above the review mirror on the inside. I was wondering if that was ablt to be fixed by putting in a replacement part or just with a little bit of work. Or am i going to have to send it to a body shop to have somebody do it for me.
thanx, Ben