Sure you can try word-of-mouth, but what happens when you wait by the phone and it never rings.
There's always eBay, Craigslist, and even mautofied.com
But what I like best is the "For Sale" stickers and signs on the trucks and especially at the truck shows. Are you selling out, yes. But you're also making it obvious that you need to pay bills and you're making it known to other enthusiasts. Times are tough, go buy a truck on the low.