rlg_67--DON'T PART OUT THE TRUCK! Man I would like to have that. My '68 SWB stepside is red, but I would really love to paint it black. Get all your receipts together, and call an appraiser. It's one of the only ways to go. Something is only worth what somebody is willing to pay for it. I bought my '68 in really great shape with 327 and 3 speed on column for $5,500. Really clean. The guy needed the money to build a house. BTW, DON'T PART OUT THE TRUCK!
nightmare--I think that's an aftermarket sliding rear window. See the gap between the ends and the center. Mine has the same thing. 1968 was the first year for the side marker lights. That's how you can tell them apart, unless someone has changed the fenders.
$5000 is pretty steep on a truck with no motor or tranny. If someone wanted that much for a rolling chassis and body then it had better be perfect with a nice paint job. Body work is not cheap though. Good luck. Oh did I mention DON'T PART OUT THE TRUCK!