Do cables come with the Infra Red receiver that connect to pro box, or can you order them seperately from bachmann?

I just purchased a GE 70  diesel dc and want to add a dcc decoder but looking inside the loco there are only 4 wires 2 from the motor 2 from the rear trucks could someone help me with this? I have found pics of another GE 70 and the one I purchased has 2 motors 1 front 1 back which makes this even more confusing I have installed decoders in other models of bach trains but I think this one will take the cake!!!! If anyone has any advice please let me know..........