[KimMG]

If you are sure this is the vehicle you want, then take it to a shop for an inspection. This way the truck can be put on a lift and the suspension and brakes can be checked. And anything else under the vehicle. Are the maintenance records available? Make sure everything works, check all accessories, windows, lights, etc. Use the keys in all the locks, check all the door handles, seat belts, etc. Sit in all the seats and make sure that all adjustments if applicable work. Have a compression check done on the motor and look at the spark plugs to see if the fuel mixture is right. If you have to have an emmissions test done to transfer title, make sure all the emmissions equipment is there and functioning. Make a list of questions to ask the owner, and don't be afraid to ask. Don't assume you know how everything works, ask.
The more you know about the vehicle before purchasing, the happier you will be with it after purchasing.