D&SNG No. 11 is a 98-tonner center-cab type narrow gauge diesel locomotive built by U.S. Steel (exact date and year unknown) using parts from General Electric (GE). It would later be sold in 2006 to the Durango & Silverton Narrow Gauge Railroad (D&SNG) in Durango, CO and given the nickname "P.B.". It is used on the D&SNG for both switching operations, as well as operating short excursion trains from Durango, CO to Rockwood, CO and from Rockwood, CO to Silverton, CO where it has remained in service ever since. It is unable to run excursions all of the way from Durango, CO to Silverton, CO due to not having enough horsepower to do so.
As of 2024, it is currently one of seven operable narrow gauge diesels on the D&SNG, the others being GE 50-tonner center-cab type diesel No. 1, nicknamed Hotshot, former Georgetown Loop DE75CT type diesel No. 1203, and former White Pass & Yukon Route (WP&Y) DL-535E type diesels Nos. 101, 103, 106, and 107.