All Classified forums require a Site Supporter subscription. It is only $25 per year and you can buy and sell whatever you like on the forum. To become a Site Supporter, go to Your Profile and select "Paid Subscriptions."
Sounds like its got some nice stuff, but its really hard to say without pics. In Texas we shy away from anything with rust. Where your from that might be the norm. Sounds more like a 4k truck with the rust issues, but again its hard to tell with out pics.
This may be 1 of those things that varies from 1 area to another. In Mass there aren't too many solid rust free trucks left. Most of the rust free trucks are restored rot boxes so if you buy one you hope the body work was done right. In Mass 5K would not be outrageous for a big block 1 ton, even with some rust.I always break in down in my mind like Irish Alley did, and to me You would have a hard time building something with a 454 and a Dana 60 for $5000.Also keep in mind that it sounds like he has over $1000 in spare parts for it you could sell off.I would show up with $4000 and have a game plan to get the truck home right then and there. Remember that money talks. I always show up with my car trailer in tow to show people I an serious and not a tire kicker.Say you can get it for $4000, sell of the spare parts for $1000. Now your into it for $3000. Fix the rust (Captkaos sells the parts) Along with a few other things I'm sure it will need and you will have a solid truck for around $4000.