Did GM make any cowl hood flapper with vacuum actuator? The flapper actuator i have is vacuum and in same place of the electric actuator. The Chevelle vacuum actuator is larger and operates with an electric solenoid.

Are you sure? I would suggest a different function for the device you're referring to. Cowls are designed to provide cold air to the carburetor at near, or full throttle. As such, vacuum wouldn't exist, nor would a reserve tank provide the instant response that the solenoid plungers give.
Where did your part come from? A Mustang?

The flapper is closed with vaccum and opens when drop in vaccum.

http://img2.freeimagehosting.net/uploads/th.ac38b55ed1.jpg (http://img2.freeimagehosting.net/image.php?ac38b55ed1.jpg)

Thanks for that jj. Nope, I don't have a clue what that's off of. Sure looks GM though.

it looks open in the picture . so with vacuum it would close then without open . some years corvettes used the same frame ,flap and electric solenoid . maybe some used vacuum .