Calling All Lawyer or Persons Knowledgeable About Cars

So, once upon a time, I was married. We bought a car together in 2018, got divorced at the start of 2019, and he signed over the car to me in our divorce papers, but we never got his name taken off the registration. Since we got divorced, he’s changed his number, so I have no way to get in contact with him. Our names on the registration are listed as “my name AND his name”. I talked to the car salesman I bought my car from for advice, because I’m wanting to trade my car in, but he isn’t sure what to do since our names are listed with an “AND” between them on the registration. Is there any way I can still trade my car in without my ex’s signature?