I went back and looked at the listing - new seller with no feedback - I smell a rat.............A new seller trying to sell something that may not exist - unless he had someone modify a cowboy. Heck, a hundred bucks and no reserve? Starting price is too low - I believe this one may be a scam.
336CB cal 38-55 presentation grade. More than likely something out of marlins specialty shop. I've seen a 336 presidential grade and would love to own it. It is in the Gerald R. Ford Museum in Grand Rapids, Michigan. This rifle is a 30-30 and is engraved all over bbl included. Very fine detail hand cut checkering and excellent wood. Just a guess on my part but I do know marlin makes all grades of firearms.