Actually pictures show that cast buffer blocks (coupler pockets to you modelers) were added in the 1940's, probably when repainted to "Flying Rio Grande".
Also, the 2 trussrods do not have threaded turnbuckles either. They have flattened ends with a bolt through, and could had been old truss rods from a D&RG B&S freight car. (B&S is Billmeyer and Small).