[SS Tim]

The add-on aluminum or steel running boards were a later accessory. Really a mid 70s and later sort of thing. Saw a lot of them on dually pickups as they became the "in" truck. Most of the time they end up looking like tacky add ons, being cut from flat stock and extrusions. Just about any old truck magazine will show you a set. Dee Zee comes to mind as on brand.

Now are you sure your truck had running boards? There were semi-popular camper steps that attached to the door and rode in and out of a cab mounted loop as you opened the door. They actually worked once you got past the look or actually needed them.

Running boards in general tend to be too high as an assist step and to me are more akward than useful. They do however make good splash guards.