Timeline on the Kelty website says they moved production from Glendale to Sun Valley in 1968, so one would imagine that's a pre-1968 pack. Info in this recent Ebay listing suggests it's 1963 or earlier. And that one fetched $150 via BIN. Seems worth the pickup. EDIT: The last post in this forum thread has a price list from that period, including all of the sizing info for the packs, so with a couple of measurements you should be able to figure out the size and model.