Bob
I,m going on 79 and Don was 4 or 5 years older than me as I recall. I have not talked directly with Don since I took delivery of the Vincent he made for me in 1972.Several members keep track of him and it seems he still shoots but they say he stopped building ,even for himself sometime in late 80's or 1990's. I get the impression he is almost a recluse.
The barrel on my Vincent is Douglass and it seems to me he was using then on his Armstrong's and Bedford's when I was stationed in Kansas. Dan, on this thread has more info on Don and lives close to him and may be able to fill you in on Don's actions since he moved to Montana.
George Hebling