I don't have any personal experience to share from the 0579 restoration. Even though we had very little interior when we started, as I recall, we did not see any evidence of additional windows. Most likely when the the car was rebuilt in the early part of the 20th century, new interior T&G was installed. We did not replace the exterior siding, and only patched the 1972 T&G (that's what the D&RGW would have done). When we worked on it 2 years ago, we still didn't do any wholesale siding replacement, so I don't think anyone knows what 0579 looks like on the inside.
I've sent a message off to my son to ask whether he remembers seeing the location of a 3rd window on the stove side 0577 when he helped re-side it last summer. (edit - he wasn't there that day)
Check NGP-V (aka The Caboose Book). There is a photo of 0579 in Antonito from the 1972 rebuild. Without anything else to help orient which corner you are looking at, you can clearly see 2 windows on one side, and obvious bracing in the middle, so it looks like there was not a 3rd window; that would be the confirmation you are looking for.
There is also a photo of 0578 being resided on page 86. This is a photo showing the stove side of the car, and it is pretty clear that there was originally a window where the stove is, and probably one in the middle also. Note that this photo appears to be reversed!
Bill Kepner
Edited 1 time(s). Last edit at 12/17/2017 08:10AM by drgw0579.