Actually I think Boulder did go out of their way for picking up things they thought might be usable and not trashing everything. Remember this was 1958 and there were still a lot of wooden cabooses out there. Maybe not too many from the RGS, but certainly the standard gauge UP and C&S cars came to Boulder on a daily basis.
I know I will always be thankful for BCRHS's help on the 0579 project. We would have eventually built our own stuff, but we followed narrow gauge tradition by using parts from other cars. But we also started a new tradition of using 0578's plans in Model Railroader !