I have a Brikmann Charcoal Vertical Smoker that I never liked as a smoker and replaced with a Char-Griller Pro that after many mods I love. The Brinkmann was in sad shape and ready for the trash, but then I came up with the idea of using it as a warming oven for a cook I'm doing at work.
i started by scraping 5 years for crude out of the inside. Then used 2 cans of oven cleaner and let it sit overnight. the next morning I sprayed it down with the hose, it was nasty believe me. I sanded it down the outside, and gave it a new paint job using 2 cans of Rust-Oleum High Heat Ultra, semi-gloss.
Because I am planning to use it as a oven I decided to convert it to propane. I bought the part for a Brinkmann Vertical Propane Smoker. I cut a hole in the bottom the just smaller than the burner cover and added the parts.
Fired it up and it worked great let burn off any remaining crude, and then re-seasoned it.