I’m very excited for you! I see major $ coming your way
If I were you, I would stop worrying about whether he broke the law, get the sheriff involved etc. Clearly he did, and clearly the sheriff doesn’t care.
I would, however, get to the Small Claims court house for that area (where the truck was at, since technically, that’s where the contract was) and file papers on MONDAY for the Kelly Blue Book value of the truck. Usually they give you a choice of having a “friend” serve him, service by mail, or service by the county sheriff/marshall office. While this usually costs about $50-60 to have him served by the men in green, it GETS his attention PRONTO.
And then of course, after you win, my FAVORITE method of collecting money is to do a Till Tap, which is where a marshall/sheriff in uniform, literally stands at the cash register all day collecting every payment/purchase that comes in in order to pay the debt. It usually only takes about 15 minutes of that for the shiester to pay up.