Southern applied white number boards to locomotives that were equipped with Locotrol. The locomotives could be used as master or slave units on those trains that had mid train helpers- as they were called then or DPU’s is the term now.
As I am adding DCC to a new Athearn GP50 I just revived. I notice something strange. The loco I am working with has a white number board #7010 and apone further research. I notice that the Southern 7003-7016 are the only GP50'S to have white number boards. All others in the fleet are all black. Can some one enplane why this is? Not trying to be a rivet counter but I find it interesting..