BoCo is a mixed-traffic diesel from the island of Sodor. He makes a cameo in Beached Wheels, being rerailed by Calley at Breakwood Park and another one in Cheesy Livi as he passes McCrakenton Freight Depot pulling a train of refrigerated boxcars.
BoCo is based on a BR Class 28 Co-Bo diesel-electric engine.
BoCo is painted in the Brunswick green livery of British Railways. The number "D5702" is painted on his cab sides in white.
- BoCo's name is derived from his wheel arrangement.