SWLM #12 wasn't a S&M Engine. SWLM got it from the Arcata & Mad River in The Eureka, Ca area. S&M had a very similar engine, #4. Both were originally saddle tank engines, that were converted to tender engines.
The S&M and SWLM had a shared trackage arrangement from the south side of Flagstaff (near the present I40-I17 interchange, south to just south of the fairgrounds (Ft. Tuthil), from there the S&M went southwest into the timber, SWLM west southeast, under what later became I17 and southeast toward Happy Jack.
SWLM track in south Flagstaff went around the south side of NAU and to the mill. S&M's track followed the west side of the main road into Flagstaff and curved off the the west to thier mill. The S&M mill is where the Holiday Inn is now.
When #12 was in display at the fairgrounds, it was located right next to the SWML/S&M right of way.
SWLM's logging operation lasted until about 1965 using a BLW S12 or VO1000 with 2-8-0 #2 (#25) as back up. It would have made a nice tourist operation.