Repairing The Cab Corners
 I spoke with several body men, and did several internet searches on best process for attaching the new cab corners. the general consensus was to use panel epoxy instead of welding. And since I am not a body man, and don't have access to a mig or tig welder, this made sense to me. Also, as it was explained to me, welding will cause some warping of the metal due to heat, and starts the oxidation process again on the back sides of the weld, and where the heat has burned off the paint. So panel epoxy it is. 

All rusted metal was cut out of the cab corner and the inside of cab corner was cleaned, sanded, and a rust treatment was applied prior to painting. I purchased the replacement cab corners, and cut off what I needed to make my repairs. I dry fit the corners to make sure I had a good fit, then predrilled three holes and threaded sheet metal screws into them to hold the patches in place. Once I had a good fit, I traced the outline of the patch onto the body, and sanded a quarter inch border down to bare metal around where the edges of the patch would contact the body. I did the same thing to the inside edges of the patch, because the panel epoxy must bond metal to metal. I then liberally applied the panel epoxy to the back edges of the patch and quickly attached the panel to the body with the screws, and used clamps and some scrap wood to keep the back section of the patch (between the cab and the box) pressed tightly in place. The epoxy sets up fairly quick, but since it was getting late, I left it over night to make sure it was good and hard.

The next day I removed all the clamps and screws, sanded off all the excess epoxy, and prepped it for body filler. I feathered out the edges, applied primer and because I am doing this work outdoors in the evenings after work, I gave it a quick base coat to protect it until I was ready to give the truck the final paint job.