are the left/right front seat foams interchangeable?

Can you put a passenger seat foam insert on the drivers side? (limited style seats)

The driver's seat has the center extension padding attached to it. If you can move that to the passenger's side foam, it will fit.

Well, I suppose in theory if you were to glue the center-foam to a passenger-foam you could make a new driver-foam!

The driver side, of course, is the one that gets worn out the fastest (well, in most cases)

I had an idea that an upholstery guy confirmed will work. Find a good passenger seat bottom (much easier than the driver side) and have an upholstery shop either make from scratch, or attach the existing extension on the driver seat bottom (the part that the arm rest folds down on) to the new, former passenger seat bottom. The hole where the power seat controls used to be on the right side won't show, and you can easily cut a new hole on the left side. The guy who did my headliner thought it was a great idea, and said he would charge me $130.00 for the job. It saves tons of money on having something new made, and will look slightly faded like the other seat since it is old leather.