Richard,
I'm not real surprised. I have a couple sets but they are very pitted. These were bare metal from the factory.
In September I was in Colorado on vacation, and happened across a Craigslist ad for some Mustang parts, including shackles. They ended up being original, from a San Jose assembled car, with the C6 part number I was looking for (matching my original set that is pitted). One of the better $20 scores I've had lately.
These are one of the default things I look for on eBay and at swap meets. They are, based on my observations, hard to find.