I don't know if you already dealt with this. But you would need the actual death certificate and you would also need to go through the court system to be named administrator or executor of his estate. Once you have that you can go to DMV with both those papers and get a new title printed and then sign over the title to yourself as the admin or executor (whatever you are named by the court) and the title will be put in your name. Then you can sell it or do whatever you need to do with it.
Complicated problem. You might need legal advice.
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