I am looking for the part# of the OEM tailight harness that plugs to the connector of the housing. Any help is greatly appreciated. Please help a MOD out.

 

Looking at the OEM xB wiring diagrams, you would have to purchase the entire car wiring harness to get this plug you are looking for. Perhaps you could find it on a scrapped car and splice it in. Good luck with the MOD's, and enjoy the Box.