I don’t know any either and my 79 K5 is even newer.....
Old square body. Those are classics and fairly tough to find that aren’t ate up with rust. Found a early 80’s Bronco in the wrecking yard over the weekend with the removable top still on it. Blew my mind that it was even back there as it should been up front with a price tag on it. Some places just don’t have a clue what they have with respect to classic vehicles.