Thanks for the help on the tar. The next area I am working on is inside the cab. I just finished sanding and grinding down the floor and there are some areas that have some slight discoloration adn texturew where the surface rust was. I found a product called Kleanstrip that I was going to spray on before I primed it. Can someone advise the best product for this??

PS I cut out the major rust damage and I am welding in patch panels this is for some surface rust.

Thanks,
Brian