I have to throw this out to the forum: over the past two years I have had an 84 TD Wagon and 85 TD Wagon an 85 SD and a 79 SD. For performance, none of them come remotely close to the 79. There is none of the smog controls, the throttle linkage is much simpler on the 79. I don't know all the answers. The 85 SD is a mugh nicer driving and riding automobile. But something about the chrome trimmed baby and her gusto for the road makes her my favorite. Can anyone verify this experience of the 79 SD being so much quicker and faster than the later models?