FWIW, I was having a dickens of a time finding one near me and online resources were of no help. I called the Ford customer service number, the rep put me on hold, then came back and gave me a list of several nearby. She apologized for the delay, telling me that she called each one while I was on hold (!) not only to make sure they had did work on F53s, but to confirm they had a lift/bay adequate for my motorhome! Ford customer service is great.
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K4EAK
2013 Thor ACE 30.1