i'll be damned...i almost bought this piece a few months ago and was gonna have mesa install the simul but they ran out of the mark3 OT's. All this time i thought it was a C. When I asked him about the somewhat indistinguishable mark on the back he said it was wire? don't remember too well...i'd still like simul tho, but it's a beautiful piece. he was a really great guy who was willing to drive it over to the factory for me so they could do the mods.