[jocko]

Then you at least know it's a 71 cab as long as it has undisturbed rosette rivets still in place. It's just likely that it has a 69-70 grille from a po. Is the inset 69 or 70 (outer is the same, inset is different between 69 and 70, if original). If you'd like to learn a little more about the truck, you could find the frame VIN and see if the last 6 or so characters match the metal VIN tag on the cab. It's usually located on the driver's side frame rail in the vicinity of the power steering pump or thereabouts. It's only a partial VIN, but it would match the last 6 digits of the cab if they are original. Also, does your truck have disk brakes up front? That' another indication it's truly a 71 (though they can easily be swapped onto earlier trucks). If your VIN says 71, and you have disk brakes, and it "looks" original, I think you can safely assume someone just stuck a 69/70 grille on your 71.