What is this canopy called? Is it a factory option?

[Claidig]

I am considering buying this truck (well buying it for my father) and the owner has told me this canopy is called a Desert Box and is quite rare...but I can not find anything at all about it online.

He was told by the dealer that he bought it from that it was an option ordered from the factory back when the truck was new and only a few hundred were ever made / ordered. The owner before that was the original owner so maybe he (the dealer) heard it through him or knew first hand...not sure.

It has a pretty cool boat loader on top but what I really like is the room in it, the big back door and the fact he has never seen a drip of water in it.

I would like any information I can get about this since I am trying to give him a fair value for his truck but not sure if this thing (the canopy) is worth $50 or $500....truck seems rock solid though so this is just a bonus if we buy it.

This would mean I would briefly own three Chevy trucks if I get this one...a 1996 Silverado 4x4 Ext. Cab...a '69 GMChevy (half GMC / half Chevy I guess...errr) and then this 1977 Cheyenne...lol