Wow! thanks for the replies, folks. I agree that an omission from the SPID is most likely what's going on here.
The other bit is the "window sticker" where the actual money is tallied also omits it. That is especially weird.
Of course, there was never an actual window sticker on these trucks in the showrooms, but it's the equivalent doc.
Maybe the guy just got a steal on the truck due to a clerical error?
Evidence that backs up the AC being factory is the inclusion of other items that were likely prerequisites for AC trucks:V8 engine, tinted glass and "special insulation" included in the "Z62 cust comf & conv eq" package.
Speaking with the current (second) owner (who has owned it for a number of years) I don't get any indication of misrepresentation. He simply doesn't get why it's not on the papers, either.
I've been looking at these trucks intently for a couple of years, now, looking for the "right one" and Oh, Lordy, I have been finding a LOT of 'kit' trucks.
Cut frames, engine swaps, driveline mismatches, etc. And, of course, LMC has sold more Cheyenne packages than Chevrolet, it seems.
This place is a great resource.
Some great info and help on this sight!
On the subject of these trucks generally, another detail question: I know about the mirror boss that indicates a pre-72 cab.... are there any other details that will call out cab year differences within the 67-71s?
Are there differences in the cab that will indicate that it was originally built as a stepside or cab/chassis?
(On the 60-66 trucks there is a filler panel used on the cab that is for SS only)
As as token of appreciation, let me offer my Brake info as a resource, perhaps, that you guys may find helpful in your projects
http://www.pbase.com/nufsed/drumbrake