Check out last month's and the new issue of Railfan and Railroad. There is a two part article in Preservation News about the building of the plows and how they were re-engined from steam to diesel. It will answer a lot of questions. Big one-there has not been one built since about 1949, so no, no one builds them anymore. A couple of railroads have spares out of service that could probably be repaired and returned to service if one is wrecked.