I have a 1972 modular/mobile that had the aluminum siding. In the course of a total remodel effort, we pulled off the metal on the advice of a local old-timer who has specialized in mobiles for 25 years. We put up Celotex and then T-111 wood in 4x8 sheets. After about 5 coats of Behr stain, the wood was finally well covered and has made a very satisfactory change in appearance, insulation and keeping out drafts. I think it was good advice. By the way, my trusty old-timer is in the process of replacing some masonite-type siding on one of his modulars after about 7 years, due to the same problems of rotting.