Dragging this topic back open again. This will be for a 2007 GMC 2500 HD 4WD Classic Diesel. 245K - farm truck.
Instead of telling you all very much here first, I'll let you see the photos. It's pretty far beyond what a coating will resolve now.
As is fairly obvious, the fuel tank starting it's descent into my driveway allowed me to understand just how rusty the rear 50% of this truck's frame really is. The LH side of the fuel tank rear support strap is completely gone. The RH is still holding, however as the photo shows, it's not far behind.
I knew the body was in only "fair" shape, two years back when I purchased the rig from the original owner. Just wish we were not looking at such a major amount of work now. The rear crossmembers are in similar slim-form. It's saving weight and getting lighter each year.
Anyone have success repairing these frames? I know this is long past any sort of warranty/recourse from GM. The engine, transmission, and most of the rest of the truck are still in serviceable shape.
