You read a lot about how weak these old frames are. With the original inline 6 obviously needing work, I figured I might as well put the money into a V8. That being said, I knew I needed to beef this frame up. I couldn't believe how expensive the boxing plate kits were! I took some measurements and got some plate from my local steel shop. The whole mid section of the truck was something like 5 1/2 inches and I got the plate something like 6 feet long. Cost me $100 but took no modification to get the whole mid section boxed up.
I had closed up all unnecessary holes and welded nuts to the inside where I was needing running board/body mounts.
Welded the full length and ground it all smooth
I ordered the 47-55 rear C-notch kit that came with boxing plates and was affordable
Made a template to fill in the missing section from the frame's mid section to the plate that came with the notch
Filled it all in
That being said I thought this notch kit was kind of hokey and I probably could have done without it. But either way, boxing was done