The first post are test loads on 55-2878 Quick Haul 12's from Buffalo, NY, Westboro, MA and Edison, NJ (Rangers)
This post has Test loads from Westboro (1&3)
The "Quick 6" I can't remember where. They were built for around big airports and in this case, GM had a program where Caddy dealers could buy out of a pool at the railhead or nearby plant and not to have them on their lot, on their floorplan. We would have to deliver them within 24 hours of the retail sale.
#3 picture is of what we referred to as an 11 Car. You have a ton of pictures of them on your Flicr account.
I love the picture of the 2600 Quickloader. When they were first built, they were too long for MA and we got stopped for overlegnth constantly. They were my favorite trucks to load. We were always with too much "Ovrerhang" which is different from overlength.