Frame Sag

[mseymour]

Hi, new to the site, was hoping someone could help with my problem. 72 blazer 99% resored, and didnt notice when i had the frame off it was weak. anyway it sags in the middle like alot of the older trucks where the bed rubs the cab, I have had to spacer up the inner body mounts to close the doors etc. I had a buddy with same truck, same problem, and he had steel plate welded under the body center to add rigidity. I know I could weld the frame boxed, but its all been powdercoated.
heres a few pics along the way