In the late 1930's, The D&RGW did considerable business on passenger trains by hauling LCL (Less Than Carload) freight in baggage cars. In the late 1930's it was common to a couple of extra baggage cars on the head end of the train ahead of the RPO car.
Eventually the unions put an end to this, as handling freight was not part of the duties of a passenger train brakeman. The unions demanded extra pay for the brakeman on the train as well as pay for the freight brakeman whose job had been taken by the passenger brakeman. The Rio Grande's answer to the problem was to simply stop handling LCL on the passenger trains. This increased the losses for running the trains and added more ammunition to their eventual quest to get rid of the passenger trains.