Don't know about actual numbers, but I have seen quite a few on ebay, craigslist and locally. I bet they were limited to the people who used them and used them up. Most I have seen in the northland (anything above Oklahoma City) they had snowplows on them and the salt ate them up for sure, the northern ones that were regularly driven had slightly less corrosion (the front fenders were still there). I have a 64 with 70k original miles and a 66 for parts I (both long fleetsides). That are more or less complete. Don't see as many of the 60-63 models though. My 64 came from Wyoming on a ranch, never got on the road much so the salt wasn't a problem, and evidently since of a frozen or dry climate, it was in really good shape.
