I took the part in to the local O'reilly's. The manager spotted right off. It is the piece that went on the back of the new A/C compressor to seal it off. I forgot when I removed the bolt, it popped off and I couldn't find it. 6 months later it shows up.
It seems it was an extra piece that wasn't really important, but I at least now know where it went.
Thanks for the help!