Make certain you save copies of that voice mail and any others you may get or still have... do not delete it.. his words can be used against him in court if it comes down to it.

Make him get the truck... I would not deliver it to him while I was owed money.

You 'tried?' Make sure you have proof that you tried. Or better yet, drive it back to his place. You can't legally hold onto it, even though he's holding onto pay.
He's LYING about planning to pay. LIES LIES LIES

Mail a letter certified mail, with a delivery confirmation... WHERE the truck is available for pickup. My viewpoint is you haven't been paid for an excessive period, you can argue you aren't an employee (you were paid to drive and you haven't been paid for your driving) and as such should not be driving said vehicle. I would not park in on your property or hidden.

Better yet... ask your lawyer.

You need to #1 cover your own butt, and #2, cover your own butt.

I don't want to hear any more about the creep liar. I want to hear about what your lawyer is doing.