These may nopt be that old, but I found them in my Dad's barn. Any idea what they go to? how many make a set? The wood is starting to go but would there be value in stripping the hardware for a rebuild?
I'd advertise / sell them as-is.
The distance between the pockets they fit into may(?) be a standard measurement.
Someone might want them for their truck, or a reclaimed wood project.
How many in a set? Depends on the length of the bed, there's probably a few standard sizes.