Oddly optioned cars and Dealership demonstators?

Oof, not a Mopar but a friend of mine, an old Master Mechanic for Cadillac, worked on a 74 Coupe de Ville that had a factory 4sp manual trans in it. He looked up the VIN and sure as ****, it showed that code on the build sheet. He also owned 1 of 2 made 2002-2003 (?) Duramax Diesel short bed pickups. It was a special order with the short box and had a unique wiring harness PN for that chassis length. Thats how he found out it was unique as no one had the harness. It hydrolocked twice on him, both times they replaced the entire motor under warranty. GM finally had a recall on the M.A.N designed injectors that tended to crack.