Went back through conversations with Rick and we did discuss and did find some 99CD's with dovetails. I'd found at least 3 99CD's on the internet that had folding rear sights in a dovetail, and at least one also had screwholes for a Williams. Couldn't see the top of the barrel on the other two.
So yeah.. seen it before. A 1976/1977, a 1978, and a 1981. Just forgot.
Now I have to pull mine out and check that rear sight.. Well, mine is pretty much NIB so I'm not going to remove the rear sight, but I see no indication there's a dovetail under it. The discussion with Rick started because I noticed on the 99CD components catalog page that the barrel was shown with dovetail and screws for a Williams.
So it's possible, I suppose, that they all have dovetails under the Williams rear sight???????????
Here's a picture of one from fall of 1976.
Another
Holy cow... another
And they keep coming... another