[sick472]

If the rust through is just at the channel and does not get outside it into the rockers, some light sheet metal angle could be used to repair just that area. My driver's side channel is now part Frigidaire. I happened to have an old fridge that donated the strips of angle needed to rebuild the channel. I cut a length of the corner of the outer skin to create the needed pieces. It's a little time consuming, but, back then...my time was free and my budget was nil.