Agree with most above. Set 706 was not a promotional set but a catalogued set from 1956. It would have been provided to both service centers and retail stores "as is" however it is always possible that a variation, especially from some big customer like Sears, would have a variation and carry it under a different number. I checked the Ambrose and Algozzini book on "Uncatalogued Sets" and saw nothing that included the Mlw GP for Sears, Spiegel, Montgomery Ward or JC Penny and 1956 really predates the huge promotional thrust of the 1960's. Set 706 included the 2338 Mlw Road GP-7, 6464-125 NH boxcar, 6346 Alcoa covered hopper, and 6257 SP type caboose. Also included were eight curved and three straight track, 6019 uncoupler section and a 1053 60-watt transformer. Paul V Ambrose in his book "Greenberg's Guide to Lionel Trains, 1945-1969, Volume III, Sets" has other information on this set which has to do with the variations in the boxes and packaging. It apparently came in at least 3 variations. Too much to type here but if you need it I can send it.
Don
