I have an '87 F150 with rusty frame rails just behind the rear wheels. (You know where all the crud from the tires gets blown up into.)

I saw your frame rail fix and I was thinking of doing something similar.

How thick is the material you are using for the side members? I was thinking of using 3/16" and just bolting them to the inside of the frame member. This way I can attach the rear spring hangers with 7/16" Grade 8 bolts, nuts, and washers.

I plan on using Rust - Mort on all the rust and sealing it with some Rustoleum Black. The Rust - Mort will return the rusty metal to its base metal form and the Rustoleum should seal it from other weather...at least for several years.

My rear fuel tank is a rusty mess along with the tank straps. Those are all being replaced with new.

Any further suggestions or direction is appreciated.

Thanks.