330 and 331 *LINK*

Here is what I remembered from the original Annual and as it was reprinted in the "Collected Colorado Railroad Annual" in 1974.
"Most spectacular development from the railfans' standpoint is the train itself. To help alleviate the chronic lack of seating capacity in mid-summer, the Rio Grande has constructed two new coaches at Burnham Shops! Original plans had been to select two former passenger cars demoted to work service, and rebuild these into new coaches. After much consideration and reconsideration, it was decided that the most practical solution would be to build entirely new cars, of all steel construction, but following closely the appearance of the old cars.
"Trucks are the only 'original' parts of the new cars; these are old-style steel beam trucks taken from ex-RPO outfit cars X66 and X122. In turn, the outfit cars received old wood beam trucks from former coaches 0250 and 0311, while the latter were fitted with freight car trucks to complete the 'musical chairs' exhange."
Hope this helps although it only outlines the swaps that were made to "truck" this first two steel cars.
Don C.