John:
The D&RGW did not sell it to the WP&Y. The US Army requisitioned it, which means the Army paid the D&RGW for it, but they had no choice. Don't think they really wanted it as it was the least used of the rotaries by 1942. It was based at Salida and after 23 was only used on Poncha Pass except for a trip down to Cumbres in 32.
Following is from the OA-OZ book I wrote back in 89.
October 1942 (AFE T-9675)
Disposition: Sold on requisition to US War Department for use on White Pass & Yukon RR. Renumbered to WP&Y Rotary 3. Taken out of service in 1947, stored in Skagway until scrapped in 1968.