I look at the Buildings, do not know enough about the RR equipment to date.
If you look at the Depot nothing is clear enough to help, look at the Hotel and it shows the concrete plinth but no vestibules, the chimneys seem to be OK. There is no bracing on the north tower, I thought that was a 20's addition.
And there is something sticking out of the ground by the Rotary?
In addition to the Pyle headlight, #58 also has the new sand dome and steam dome cover that were put on late. These came, as I recall, from a C&S switch engine after The original domes were cannibalized for a CB&Q engine that was being displayed somewhere. So this was after #58 had been returned to service from the dead line.
I agree with Jim, probably 1935 after the roundhouse fire at Como, and maybe after #75 and #73 were wrecked on Boreas in January 1936.
According to Hol Wagner in the Burlington Bulletin #45 when Burlington's 4-4-0 359 was brought into the Denver shops for conversion to exhibition engine #35 in 1932 they needed to replace the modern domes on 359 with older domes. Since 58 was in the shop and had original 1886 Rhode Island domes and the diameters were similar the switch was made and 58 had modern rounded domes. 58's original domes can be seen on Q 35 at the Patee House Museum in St. Joseph, MO.
The Steam Dome on 4 just needs lagging and the outer ring and upper cap. The Steam Dome is actually sealed with a copper ring and the cap bolted on to the dome itself, it has nothing to do with the "Pretty" around and on top of the dome itself, with the exception of the lagging put around the dome itself.
As little of the 4's Steam Dome is exposed, it will be more cosmetic than functional.
Thanks, Ken. I'm going to still guess this photo was taken in '35 or '36, as that Pyle headlight was put on late. I can't remember where I read about #58 making a curtain call from the dead line, but I believe it, although we know that #72 was fitted with a small Pyle headlight after the 1935 fire. If they only had one large one available, #58 would have got it.