Hi oldM,
The three places I'd list it are on Ebay, Craigslist, and the MVPA classifieds. And of course on Steel Soldiers and this site.
Should you make anything for helping him figure out the value......dude, that's purely your call. Not much more to say there.
I don't think you have enough info to even begin to figure out the value, but once you get a good look at and post some pics here I'm sure it will make for an informative and lively discussion. Ultimately it's only worth what someone is willing to pay for it, and that depends on who sees it listed and when.
I don't believe there is a set reference for MV prices, like a Kelly Blue Book or something, but even if there was the condition of these trucks is all over the map....so I doubt a listing for Excellent, Good, Poor, etc wouldn't really be useful.
So take a look at the ol' girl, get some pics up, and let us throw some numbers around.
regards,
bob