ask for 30 more pictures and if he's willing to give up the VIN, you can run a report on it for history sake. If you test drive it, tell him not to start it till you get there. You want to be there for a cold start. Then test drive it and I mean TEST it. I put mine in 4lo and 4hi and drove around on the street some. 



, if the truck in the link above looks and drives good I would think an offer around 3g's might get the deal done
I would even hit him lower with a wad of cash and go from there.