Six pack carb mods

This is a six pack question so I'll ask it here instead of starting another thread. I have a set of the Holley replacement small block six pack carbs that I nought new about 3 months ago. Does the center carb have the power valve blow out protection that Holley has put in the later carbs, or is my carb an "exact replica" of the old carb that needs to have it added?