Access cab body vent question...

Does anyone have a picture, diagram, or general idea of the location of the main body vent(s) for the access cab?

I have been told that I should be able to see them between the bed and the cab body, but I haven't been able to locate it/them.

It doesn't seem like the cab is vented much if at all, since the air pressure with the A/C fan on is high, and is obviously relieved significantly by cracking any window. I wonder if the vent(s) might be stuck or painted shut.

 

I don't have any pictures of it but the vent is on the rear wall right in the middle behind the cover panel. I would say that the vent is about 3-4" wide and about 1.5" tall. I will be taking my rear panel off within the next few weeks or so to make my sub box in the back so I could take some pictures.

 

I can see mine between the cab and the bed, it's right where cotruckin is saying it is.

 

It is hard for me to see the vent with the topper on. Where it comes through there is a 90* turn down into the cab.