In January, 1963, my uncle was working as a mechanic at a Studebaker dealership in Broohhaven, Long Island, NY, when a new Avanti, 63R2159, was delivered. Two years later in 1965, my uncle bought that Avanti from the original owner and enjoyed the car until he passed away in 2008. I bought the car in 2009 from my cousin. I have finally started the full restoration and I am at the point of removing the body bolts and lifting the body off the frame. Everything from the body has been removed and is just a fiberglass shell. The chassis has some rust damage but is repairable. The body bolts that screw into the hog troughs are not moving and I broke the head off of one already. Being that the bolt threads are not accessible, has anyone come up with a way to get these out? Should I cut small holes in the hog trough to apply penetrating oil to the threads? Can I use heat without damaging the fiberglass? Luckily, the hog troughs are solid with no visable outside rust. All the other body bolts with exposed threads I have loosened so they will not be a problem. Any help would be greatly appreciated.