Just use
https://www.escrow.com/index.asp
You're protected and he's protected. They have been around for years, and it works fine. I've used it for many watches.
A few things to work out with him:
1) Who owns the truck from the time the escrow deposit is made? If it's you, you have to insure it and be sure they know that it's in transit.
2) Are there any fees due him, if you call off the deal due to condition?
3) Exactly what is your "agreement" as to your inspection and purchase? I would recommend a complete inspection period upon his arrival, and your ability to cancel the purchase if you're not satisfied with the truck, no conditions. In exchange he keeps a small portion for expenses, say $300 or $500.
If you feel strongly that you've done your due diligence on the condition, history, etc. on this truck, then your chance of turning it down is not really that high, unless he's really hiding things. If he is and you turn it down - it's the best $300-$500 you'll spend. You will also do a better job next time on initial evaluation.
Just an option that offers protection, and options. Don't forget the insurance. If you don't specify it, you will own the truck at deposit (when you executed a purchasing deposit for it) and if there is a problem (wreck, damage, vandalism, hail, etc), you will pay the price.
I hope it works out for you.
saa.