In that case. I would take it to a good body/frame shop. Have them look it over real well. If it had a new cab put on, all of that should be good to go. But, I would be worried about the frame. Make sure everything is lining up right and all of that good stuff. If its not, you can get early wear on stuff that should last a long time. If that is good, offer 16.5 since it is a salvage title and go from there. Prolly still be a good truck.