Tricky one, depends upon your market, and what it owes you. Looks to be in good condition, good paint work, rest of it looks OK from the photos, only a couple of down points that would worry me, bubbling of the paint on the front of the bulkhead, and the rear spring hangers where the chassis meets the rear cross member needs some attention. The rear springs could do with replacing, but they're cheap anyway and not something that would put me off, just a haggling point.
Truck cabs seems to be quite in season, I like them, as do quite a few others and should be a plus point to selling. Rocky mountain door tops a definite plus point!! The inside is very tidy too, chassis looks solid from the pics. I'm thinking somewhere around £1500 realistically, if I were buying anyway, or maybe aiming at £1750. Have a look through a few other that may have photos to try and place it in the market, try autotrader online, ebay, some garages etc have piccies & ad descriptions that may help.
Sort out the rear spring hangers or you may lose a couple of hundred from the price, or put off most buyers completely.
Where are you at? There may be some that wish to come and view...