The 4020 and the 4002 series actually use the exact same cabinets, same part numbers and all. The only difference is the dress panel and the internals, of course. They were available in 2 sizes, a single bay version (like mine) and a 2 bay version (which is slightly more common). I am far from the first to have one of these as well, a few other people had/have a 4020 besides me.