I have had this smoker for over 20 years. I think it is what is considered an offset smoker. A customer built it for me as partail payment on a boat dock. It is built very well 16" diameter by 1/4" thick but after researching a big RF build I decided to check this thing out. The CC is 16" x 31" ** FB 16" x 17" ** FB Intake is 4" round ** FB to CC is 9" x 9" ** and Exhaust is 3.5" ID pipe x 30" long. According to Feldon calculator the FB is way to big, the vent is to small, exhaust to to long, and FB to CC is way to big. Since I own a welding shop I would like to correct these issue and if possible make it RF? What should I do to make it right? I was thinking close the FB to CC opening to correct size, open vent some and shorten exhaust. And if I could make RF I would do that also and then move exhaust to other end. I will post a picture as soon as I can find one.