replacement A/C roof vents

I want to know a source for replacement A/C vents. I would like about a 6" square or rectangle, not the factory round ones. I would also prefer that it could be closed or "aimed". I want to put a "down draft" vent in the bed room A/C unit so all the cold air is not being directed into the bathroom and closet.

On a similar note the bedroom unit could use some additional duct tape to seal it up better.

Found one! I will post pictures of the install when it arrives.

Alan, what is the diameter of the vent hole in that one and where did you find it? Thanks

Ray here is a link to the item on Ebay and here is the dimension of the 4 inch diameter vent.

it is done

Here are the pictures of the install.