The model name stands for broad gauge (W), Diesel (D), Mixed traffic (M) engine with 3300 horsepower (3D).Serial production started in late 2005 with locos being allotted to almost all major BG diesel sheds.[1] The loco features left hand drive, WDG-3A style High Adhesion bogies, air cylinder under foot-board, WDP-4 style fuel tanks, engine doors like WDP-4, marker lights outside cabin doors, electronic horn, High capacity buffers.Components and auxiliaries have been improved with the aim of making the duty schedule longer between maintenance visits to the shed.It also looks the same, shares the same body shell, control cabin, undercarriage and the high-adhesion bolsterless bogies of the WDM3D.The WDM3B seems to be the result of the Railways trying to cut the WDM3D down to size by eliminating its troublesome features like microprocessor control.[4] This was an experimental class developed out of the WDM3D by IR on the ever-lookout for more power, all equipped with High Adhesion bogies and roof-mounted DBRs.[4] The very extremely rare WDM3F was the result of the last and final experiment in IR's drive for more powerful ALCOs.On 27 July 2020, due to over-aging of existing Bangladesh Railways locomotives, IR gave 10 WDM-3D units for free under its "grant assistance" plan.
Class M10
Class BED-33 6536. Formerly 11587 of Samastipur, this WDM3D locomotive has Auxiliary Power Unit (APU).