 Comparing with the WDM3A, the WDM3D can carry 1.5 tonne more axle load and generates 8 tonnes more Maximum Tractive Effort.The engine is classified WDM3D though it outputs only 3300 hp and not 3400 hp as the name should suggest.Earlier WDM3Ds had issues with their electronics which probably led to the interim development of the WDM3B in 2005, basically a lower powered WDM3D without microprocessor control.