(by Jeff Witt:) This is clearly NOT the G&D, nor one of John's locos.
My bet is that the loco is Jim Dechert's (no weathering, and I've never seen it before, nor is it mentioned in "The Book"). For sure the guy hanging on the tender has been in many of John's pictures before. However, I'll bet the layout is Jim's. Those figures of John's were pretty mobile creatures!!!
Also, check out the "forced perspective" on the mountain; trees get smaller as you go higher. Then, at the top, the mountains blend into the background. Shades of "Mt. Alexander"? (see "1952 Model Railroad Handbook" acticle).
JA was quoted as saying he wasn't an innovator, but picked up techniques from other folks and applied them to his modeling ... Jim Dechert was his elder, a real veteran, he may have been a mentor to John.

A couple of other items:

• Look how small the rail is...code 70? Was that even available then?
• The coupler on the gondola at the right edge is a.......BAKER!!!!

• He shows up in the "Western Model Railroads" article that the "wreck" appeared in (Oct. 1948 MR), with a railroad named "P & T"
• He built a gondola for John (Trackside photo, June 1954 MR)
• He has seven articles in Model Railroader, dating from 1934 to 1937, dealing with issues like HO as a space saving gauge and two-rail wiring!!!