What can I realistically get for $15k in CA? Or is it smarter to use it as a down payment?

I’m in California and sitting on about 15k. I’m trying to get into a diesel truck i’m hauling equipment everyday skid steers and mini Ex. mainly looking at 5.9 or early 6.7 Cummins, something clean inside out and I can use as for work daily and also use for weekend work runs and also go do outside runs.

But I’m torn…

Is $15k enough to find a decent, reliable Cummins in this market? Or would it be smarter to throw the $15k down on a newer / lower-mileage truck and finance the rest? I haul with a 21 2500 mega cab super clean bighorn with high tech top of the line bighorn. but i want Just something solid that won’t blow up my wallet day one. Good engine, clean frame, not trashed and passes smog in cali.

Anybody in CA bought/sold in that range recently? What should I expect?