Hi Andy,
If they are rusted pretty bad, soak them down with your favorite penatrating oil and let them sit for a day or two. If they are really bad, I have just kept them damp with the oil. Some of them took a couple of weeks. Every time I went by the truck, I would squirt some oil on them. I have found that with some of the old bolts, if you tighten them just a little, and then loosen, they will come out. If you break them off, then use a drill to drill into the old bolt shank and a screw extractor tapped into the old shank and turn it out. Once it breaks loose it will come out pretty easy. Good Luck.
Hope this helps.
Mark
