My sister recently sold a car on line using a nation wide service. They take hundreds of pictures and put it up online with your asking price. If it sells, you should be happy you got what you wanted. When they don't sell, you can lower your price or hold out for another couple of months to keep trying. My sisters sold at the the first price she asked, not super fast like a lower then it should have been, but what the market thought it should have been. She did have to pay a sellers premium, but it wasn't too bad, she just added it into her asking price.
Its your truck, ask what you want for it, not what you think it's worth to everyone else. Hemming's Motor news is a good place to look around, they should have a listing for such trucks with a selling history of what others have sold for.
You have had that truck for close to 50 years, surely you have an idea what you want for it.
