You need to create a list of the things that should be better and need upgrades but please be realistic don’t just write all the possible things you need to make difference what is normal and expected to happen and what is clearly damage and needs fixing.
Use the list you created when you start negotiating about the deal prices and terms.
Put the list written on paper on the table between you and the person who you negotiate and go item by item and explain and describe to them that you want a discount.
The list will make your position stronger and that will lead to a better deal so use it to gain advantage.
2. Perform the Mileage Check Of Straight Truck
Mileage check is very important because sometimes people that want to sell you the trucks may do some mileage record modification and you may expect to see lower mileage recorder than the actual and ream mileage is.
Try going trough the entire paperwork to see if there is any difference between mileage recorded and the mileage display and also it would be a good idea to go to a straight truck dealership to see maybe they can do background check of the truck.