If I recall correctly, Ernie Robart compiled lists of every freight that ran from 1965 or '66 until D&RGW operations ended. I remember that they were quite detailed, listing all loads with origins, etc.
As for on-line shippers, I know that the lumber company in Durango was shipping east right up to the end. I believe the small sawmill near Juanita was doing the same. I remember seeing some flats sitting there waiting to be loaded on a trip to narrow gauge country I made in 1968. As I recall, the Chama lumber mill was also still shipping. Coal also moved east from Durango and Monero to the power plant in Alamosa. As an interesting aside to that, when I was on a Friends crew about 20 years ago, removing the three-rail switch at the Alamosa power plant to take to Antonito, we made an interesting find. While digging around in all the cinders and slack coal around the switch, we found the buried remnants of an old Valley Courier newspaper. Strangely, it was part of the front page of the newspaper describing President Kennedy's funeral procession in November, 1963.
I believe the Pepsi bottler in Durango was still getting some inbound supplies by rail right up to the end, too.