I have a 1984 GMC Sierra 2500, extended/quad cab, 6.2L diesel engine, all original with less than 100,000 miles on it. It was my husband's grandfathers and spent many years in a shed before we started driving it, now hubby has a new truck and we're looking to sell this one but no idea what to price it at. It has all the original interior and exterior, some rust starting on the outside, it's black and red, has power windows, power locks, a/c, cassette player. There are no rips in the seats or cracks in the dash, it's really clean in there. I'm not sure what else would be relevant information. Any ideas what it might be worth?