I would be a bit leery of that -- the advance payment -- although it may be completely legitimate!
As far as checking, try
Carfax. You can input the VIN and see if the truck has a clear history... Good luck, whatever you decide!
If you get really desperate, my old H2 is for sale at
Music City Motorsports!
But, it is "pewter" -- not silver, and has the wheat interior, not gray, as it is listed! Don't know WHY he can't get that right!