Atlas Gold 10003834 Alco S-4 GTW Grand Trunk Western #8204 DCC & Sound HO. Picture may show a different road number. Alco introduced the S-4 in 1950. The S-4 like the earlier S-2 was a 1000 horsepower switcher. Some 636 S-4’s were built for North Americanrailroads. The primary quick spotting difference between the S-1/S-2 and the S-3/S-4 can be seen in the trucks. The S-1/S-2 has Blunt trucks,while the S-3/S-4 has AAR-style trucks. The versatility of the S-2’s and S-4’s were evidenced by their service in mainline railroads, shortlines,and industrials.Features Include:Newly tooled with improved cab design5-pole skewed armature motor for reliable operationDual-flywheels for maximum performance at all speedsFactory-equipped with AccuMate® knuckle couplersExceptional painting and printingSturdy die-cast mainframe and gear casesSound Functionality Features:ESU LokSound decoder, supporting all DCC programming modes.Flexible mapping of function keys F0 to F31.Follows all NMRA DCC standards and recommended practices.Over 20 sound effects are available, including engine start-upand shutdown, prime mover sounds through all eight notches, bell,air horn, air compressor and more