Thanks. The thing that really tipped me off was the lack of any other numbers like a date code, etc., and the fact that it looks like that area has been machined down. You can see sharp edges at the top and bottom of the area that I don't see on other carbs. In fact, on the top, there is a step where the surface changes elevations. Thanks for the second opinion. Looks like I was right to be concerned.
Thanks again,
-Keith