Well Fatman, I can tell you that this locomotive is one of the hardest to date as Marx made many overlapping configurations. Here is what I got from your pictures and I believe its a good match.
1949-1952, catalogue no. 495, black cab, black boiler, silver and black sideboards with red trim and crest and no lettering, silver pilot, dotted glass headlight, black headlight rim (this is the one detail I can't quite confirm from the pictures), tinned smokestack, tinned sheet metal boiler front, tinned dome, tinned marker lights, 0-4-0 wheel arrangement with Baldwin drivers. In addition the one piece sliding shoe electrical pick up for the motor dates from 1946.
Hope this helps
Don
