Help with throttle body part identification

Help cant found what this is . Some kind of plunger there's no electrical connector I don't know if it's something with my cruise control? Like I said there's no electrical connection so I'm not sure what it is or what

 

Not sure what that diaphragm does but, there should be a vacuum line attached to it.
Oh, and it's a throttle body, not a carb.

 

Dashpot. Keeps the throttle from slamming closed when you let off gas.

 

Theres no vacuum port on it. Would there be a difference between auto and manual trans?

 

Like vasinvictor said it’s your dashpot. It slowly closes the butterfly in your throttle body so it doesn’t stumble when you let off the gas suddenly.

 

Not sure of the trans differences... mine is exactly like the video.

 

Throttle opener and dashpot are two different things.

"Dashpot" slows the last few degrees of throttle plate closure to improve driveability. Not found on auto trans t-bodies. It's a stand alone piece with no vacuum connection. The black thing in the OP's pic.

"Throttle opener" holds the throttle plate open, just off the stop screw when the engine is off via light spring tension. It's sole function in life is to allow extra air flow for the starting process and nothing more. When the engine starts, manifold vacuum (little hose) acts on the diaphragm to overcome the spring and allow the throttle plate to close against the stop at the normal idle position.