Reference the New Mexico Railroader, Vol. 10, No.1, 4/1968 that has a "List of Narrow Gauge Operations in 1967 compiled by Ernest W. Robart."
Under the date for July 10, 1967, the report states "Engines 498, 497, 21 drill mud, 18 pipe, 10 idler flats. Note: 497's first run after class III overhaul which was completed in late June." This was a move from Alamosa to Chama. And it is the one I photographed starting at the Alamosa roundhouse.
Also on the same date, from Durango to Chama was this movement: "Engine 483, 4 lbr., 1 flat that got hit by a falling tree on the Silverton Br. over the winter. Pick up flat with damaged air system at Oxford from train July 5. 6 cars into Chama. Intended to pick up the coal car at Oxford and 18 stock cars at Lumberton but crew decided against it."
Then in Vol 11, No. 1 of the same publication for Jan. - Feb. 1969 is this item: "Date 4/23, Alamosa to Lava, Lava to Alamosa, 476, 478, 1 caboose #04343. (Break-in-run for locomotives after light overhaul over the winter.)"
So, a Class III for the 497 and a "light overhaul" for the 476 and 478.
Copies of this publication arrived today in the nick of time for this discussion from Roger Cook who was chasing many of these trains during that time period when he was attending nuclear weapons school at Los Alamos while he was an officer in the Navy. He was the nuc officer on the USS Hancock, and this schooling offered great train chasing--of course it was Vietnam right after that, so Roger switched to taking pictures of the one operating rail line in S. Vietnam.