As I stated before, some of the styling cues from this fiberglass LaSalle styling mule (and the La Scala concepts of the same period) were adopted for the Gen II, FWD Seville, introduced as a 1980 model. GM's FWD drivetrains in 1973 were under much larger cars. Further confusion may come from the internal GM nomenclature for the "X" platform on which it was built. X-cars of the 1980's were FWD.
There was another La Salle concept in 1974, which was very close the production Seville in everything but name.
So, I'll tweak the header a bit - does that work for you?