Re: 4000 series

Boxcars in the 4000 series were all of about the same width - 91" as I recall. There were minor variations in height - the differences were in length. There distinct classes within the 4000 series ie., 4000-4099, 4100-4499, 4500-4549(?)etc.
They had METAL bolsters. Frame sills were largely 4 X 8 opposed to 5x9 and 4 X 7 of the 3000 series cars which were a couple of inches wider and taller and all 30 feet long.
4000 cars were built with center continuous drawbars and the trucks were Thielson Swing Motion. By the 20th century the cars that had been lengthened had been changed from "CC draw" as it was termed. Some cars had been changed to the D&RG archbar truck and as years went on and their numbers were reduced the survivors acquired a truck change. They utilized the "split brake" system in which the brake cylinder and reservoir were not a one piece assembly but joined by piping. There are one or two cars still at Chama, the 3000 boxcar behind 278 and RGS 1789 at the Museum that still have split brakes which were all but elininated during the rebuilding.Also some did have metal roofs of varying styles at least as early as 1904-5 including some "inside" Murphy roofs (found on some C&S cars). I never have seen one pre-1923 with the "outside" Murphy roof(XLF Flexible)that was used during the rebuiding. But until you see a photo of everyone there always a chance...