I have a '51 M that we recently bought at auction. The tractor was sitting in a shed for the last 10+ years and the engine is loose. We're working on getting it running again. Whoever parked this tractor the last time left the fuel in the tank. Needless to say, it has turned to shellack. We need to do some extensive work to the fuel system and carburetor in general but found a massive buildup of sludge and a ring of rust where the fuel level was (about 1" deep at bottom of tank!). Does anybody out there have any suggestions other than replace the tank entirely? The tin and tank on the tractor are perfect and I'd hate to have to buy a 'new' tank that will not match.