Wiring harness

Does anyone know why there is 2 seperate radio harneses in a 2nd gen ranger

some Rangers have the Premium Sound System in them. if it does have the Premium Sound, it should have a square looking plug along with the 2 rectangle plugs. if it doenst have the Premium Sound, then it just has the 2 rectangle connectors.

one side is power and ground and lights, other is speaker wires.