Can somone tell me the name of this part?
 

I've always been told "no question is a dump question?" Well here goes...I'm trying to figure out the name of this part. This is the back of the engine block from an '07 Dodge Ram 1500 V8 5.7l Hemi.

Before the transmission can be bolted back up, I need this part. As you can see I have it circled in red. Is it a gasket? I just need to know the official name so I can order one. I went to AutoZone, and unfortunately nobody in the place knew what it was called nor could they find it in their part books or computer.

I'm at a loss.

Thanks for any help