Dave,
I don't know currently where you might find long mirror arms, but they do come up on Ebay occasionally. I will keep an eye out for you. If you can see from my pictures, the drivers side is fixed length ( I believe stock) and the passenger side is adjustable. That is the way the truck came to me and I just cleaned them up, painted and re-installed. So they are mismatched, but hey, it is a farm truck and part of the "character".
Kent