Ya, I had to go back and re read just to make sure I understood the question.
I am really curious as to where this tender came from, and when. Are there any documents out there that show in service dates or perhaps where it is from??
It could be from a random C-16 that missed the camera lens, or anything smaller as there is not much for historic pics of these engines. I have never seen evidence of a similar (or this) tender behind a C17 - C19 but it could exist. It is not from the 360, 361, or 375 that I can tell. It has a very similar appearance to a K-27 tank, but I can not find one that matches the rivet patterns. Definitely not from a Larger K. It could easily have come from another railroad, and I have looked into some of the RGS engines, but no success yet...
I studied the side and rear of the tender for about 30 minutes on our last trip trying to catch a glimpse of any leftover writing or numbers on the body. To my naked eye, none were present....
Again, my resources are limited to pictures I have taken, purchased, or found online, and is not vast. I will definitely post something if I discover the answer....
Casey