William, that shot of 488 was in Chama in April 71. The D&RGW records have no info on the changes to the tender coal bunkers. I do not know who or what determined what when in the D&RGW record keeping. I first thought it had to do with the dollar amount, but the records have some small expenditures but leave out some that were costly. Makes the research difficult.
Attached is a photo by Kindig in Gunnison in 39. Sometimes the only way to determine when something was done is to look at the photos.