I think you have that backwards. The big back window is the rare one. Just go down the completed auctions and see how many big back window trucks there are compared to the small ones.
For those year trucks the big back window is the rare one,however it is a long bed which is less deseriable i think that if everything was done right it's not a bad price but a hard sell [long bed]. As said many time before they are only worth what one would pay for it.