W123 Seat, can you made a left from a right?
 

Can a 82-85 W123 left seat be made from a right?

You can swap the bottoms, no problem. If you swap the backs, it puts the back recline adjustment knob on the inside. It still works but looks odd. I've not found a way to change that feature.
You can move the flip up arm rest - both backs have the proper hole on both sides.

Moon,
You come up with some entertaining questions !!
I think you could do it, but if it was a manual one, the controls would be a problem especially the tilt winder. You may need to make some brackets so that the mounts were in the right places.
Good Luck if you try it !!!

Swap the tracks so you keep the height and forward/back levers in the same place. Recline winder is the only problem. The bottom springs and the bottom covers are the same.

I swapped my manual seats (who has power!?) in the 83 just a few months back.

I tried to pull the tracks off, but ended up with a few screws on the drivers side I couldn't get. So I kept the tracks, and ended up with the "odd' control position. Everything fits just fine, and it's really quick this way, I'd say an hour if nothing hangs up.

Now it's easy to recline the passenger's seat while you drive. That's...handy, ha.

Caution..There were changes in the 85 seats. At least in the two "Euros" I have. The back of the front seats are totally different, no nets just a curved plastic back, They both take the same cushion however. IMO the 85s are a "cheezer" seat. Also the seat belts used a smaller "receiver. I swapped out the 85 seats for "early ones" You will see right away if those changes apply to the US "85s", just check the front seat "backs"

Damn, 2 '85 Euros? I'm officially jealous.

The seatbelt receivers have to come out to get seats out anyhow (I think). Apply blue loctite when you put them back in.

I have never been able to figure out how to unbolt the tracks--the bolts are sandwitched between the tracks and seat frames and are inaccessable.

I have used passenger side upholstery (and sometimes the cushion) on the driver side many times. The driver side upholstery goes first, so finding a good passenger side is easy. This works for the seat bottom, and the back. You can't go the other way because you will have a hole on the vinyl (or leather) where the arm rest was. I find that buying a "seat cover" is less expensive at wrecking yards, than buying the entire seat. I get them at my local self service yard for 3-10 bucks each piece. I recently got an entire set (front, back, top & bottom) of "seat covers" for my E300 (gray leather) for $3.99 each piece.

You have to slide the tracks and align a hole with the screw. Large phillips head as I remember. You may have to use a lot of WD40 to clean and lube the tracks to make them move.

I just put a right hand seat out of an 80 240D in the driver's position in my 77 240D. I switched the tracks and the seat belt mount, and the seat recline knob is now on my right. Not a big deal at all, and now I don't have to sit on a pile of cushions anymore.

Yes, I sure did!

Actually before I could remove the seat in my car, I had to wedge a 2x4 behind it and use it to pry the seat forward and up, as the height control tracks were totally frozen up. I couldn't even see the rear track mounting bolts until I did that. They're a little better now with the addition of a lot of penetrating oil, but still pretty stiff.

got nets on mine

Well like I said "maybe its a Euro thing"

my 85 euro has nets...
they're leather though... (the seats, not the nets)