Here is my short version of the truck story.
The Stock cars and Reefers had Andrews style, 4' 8" wb Trucks made by ASF. ASF pattern number 7385, When the first 25 Van Dyke Tank cars arrived in 1937 they were equipped with trucks removed from 5900 series cars.
After about a year the D&RGW required UTLX to obtain their own trucks from ASF. ASF responded with a modification of the original design with intregal journals, ASF pattern 7385A. ASF never calls them a Betendorf truck. (different company, I think)
Upon reciept of these new trucks, the stock car were placed back on their own trucks.
When the White Pass obtained the narrow frame tanks from UTLx they had the Arch bar trucks swapped for the ASF 7385a trucks. The guy in Montana then purchased the Arch bar trucks from the scrapper. These are the trucks to be obtained from Alder Gulch. (If the trees growing up through them can be cutdown.)
Any way thats my story and I'm sticking to it!
Now a question to ponder is what trucks were under the 25 5900 stock cars in the intrem period. 3'7" perhaps