For all who have rear engine coaches (at least Regencies)heads up! While doing my after trip shining and cleaning I noticed the stainless shelf above the rear bumper seemed to be loose and thought "Oh well some new rivets will fix that". However upon closer inspection from the inside I poked around the square tray that is removable for engine removal and found the square tube was rusted completely through. This tray has four bolts holding it in place and is removed to allow the engine to be removed. The steel tubing is a welded rectangle with stainless sheet as a dressing. I am in the process of removing the stainless sheet on each side (the tubes are not removable on each side where the batteries and the coolant tank are located). I plan to remove the center section and build a new one, then reinstall the stainless sheet and replace. I will drill weep holes along the bottom of the tube and will not reapply the caulking that came originally. This probably held the moisture in the joint and contributed to the decay. Since this tray is part of the primary structure it is critical to have it secure and solid. I will post pictures as I get this apart and as it goes together again.

The project has gotten bigger and more serious. Once I removed the aluminum sheet I found the underlying steel completely gone! A quick check for galvanic corrosion in Wikipedia shows the answer: The corrosion attacks the steel first and more aggressively. Am now replacing the steel cage and having the new tube steel powder coated in addition to an insulating tape. For those with small bubbles along rivet lines you probably have the underlying steel tube basically dissolved. A good winter project for those of you up nort!