Yes, rear disc was a stand alone option beginning in 79'. Just not that many were ordered with the option. Most ordered the WS-6 option as you know, which came standard on them. This is only about the 3rd one that I have seen that was ordered that way. I too thought the stowaway spare was last used in 79'. I could not find it listed on his window sticker as to what type spare was in that car. My window sticker lists it.