The only drawback is it pits the steel some, but I can just put a skim coat of bondo on the outside frame rails.
Has anyone used this from Eastwood? It has good reviews, might work nicely on the inside of the channels....seems a little pricey.
http://www.eastwood.com/internal-fr...C__vOD7vh4NqIgV5RI4C7fVV9L0rc_KbQdRoCMqPw_wcB