When I put my bed together in 2010 I left the boards un treated, I did use the truck for trips to garden center to pick up sod and pavers, things like that. I Leave the truck parked outside most the time. I was surprised after a few years the pine boards looked still looked new. In my area they just don't weather. A few years back I rolled them in place with black paint after learning on this forum they came black when new.
Your weathered boards fit the stock appearance of a working truck.
