If the insurance co will fix what you have then do it. If they are totaling it fight for no less than 8-9 grand. Is it a 12 valve? if it is used engines go for 3-5 grand.Even 24 Valves bring good money on the used market. You can part it out and clear 10 grand ,I hear front fenders go for 2-3 hundred bucks each.Don't know what the 91 -92 Dually goes for but a friend sold his for 8 grand a few months ago. If they want less than 5 and all is good with it ,,grab it.