It's a former D&RGW unit, more specifically, a 5380-5390 series unit. They had externally mounted MARS gyralites. SP (or a successor)removed, and blanked them over, hence the bare steel.
Yup, around Denver it's like shooting fish in a barrel! Yesterday I saw the (very long) Barnum and Bailey circus train heading north on the Joint Line... without my camera! Unfortunately, I've been spending too much time on the islands and not enough around here!
The trucks on the GP40s seem very different. Both Blomberg M and Blomberg H. I presume they are a GP40 and a GP40-2 difference?
7965 is running on Bloomberg Ms The DRGW unit appears to be running on trade-in Bloomberg B trucks. The SP must be a 40-2, but I don't see the Water sightglass The DRGW is probably a GP60.
The 7110 and 7640, it's hard to tell. They may just be different GP40-2 runs. Although I still don't see the sightglass.