Cool, from my experience anyway, carb cleaner is pretty good to get some stuff off grease grime and oils, but it works pretty poorly to remove the varnish of old fuel. Yeah rusted tank is a pretty tough break there. Good to hear someone else unearthing these old girls too.

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2003 Dodge Ram 2500 Cummins - Georend fully built trans, Banks Big Hoss Bundle, Smarty Tuner, 5" turbo back exhaust. 500 HP and 1100 ft/lbs to the ground.
1979 Mercedes-Benz 300CD - Lost to a four car pile up on 275, Thank You Michigan Drivers.
1986 Mercedes-Benz 300D - Sold, Euro non-turbo car.