I suspect it would be more common on an Imperial LeBaron than on a similar Crown, just as it would be more common on a New Yorker than a 300. Just considering the customer demographics of each carline. Seems like it might have also been available on rh bucket seats, too?
Usually, the floorpans were not symmetrical from side to side, so the seat tracks would probably not be the same, side to side. That would have been "too easy", back then. A GM division might have built the pieces which made up the mechanisms, but they would be unique to each brand of vehicle. Just like Saginaw Division might have built the steering columns, BUT they were built to the specs of the OEM customer rather than everybody using Saginaw's desired specs. On my '80 Newport, the outside of the column looks very similar to what came in the same year Chevy Caprice, but what's inside and makes it work are completely different, as I discovered when I had to replace the turn signal switch on my Newport. In many ways, the Chrysler columns always had a more quality feel to them, which might have been due to the possibly better-quality grease used on the metal bearings and races than GM would pay for on their own columns. If GM saved 2 cents/car by using less expensive lube and a bit less of it, it would mean significant profit increases when it was all figured into their greater volume of vehicles. If Chrysler spent an additional 4 cents/car, in order to get that better feel, rather than "good enough" as GM might do, a minor adjustment to a few other things would more than compensate in the grand scheme of things.
Enjoy!
CBODY67
