Dave P-
https://www.etrailer.com/Accessories...ha/3027-P.html
I note that etrailer says this adapter works for:
2004 - 2015 Freightliner SL Series with factory Tow Package
2004 - 2015 Freightliner XC-Series with factory Tow Package
Or, this one from eBay:
https://www.ebay.com/itm/Freightline...-/142448862415
I just know about these adapters; you should confirm for yourself that they are correct for your application.
I had to look up your Phaeton model in your profile. To make it easier for the next "helper," you should add a "signature" to your profile. It contains whatever info you want; most people put info about their coach there, so they don't have to type it into each message. Instructions for adding a signature are
here.