Are the seat cushion interchangeable from driver to passenger ?

Yes

Yes for movable seats.
Some late passenger seats have a harness for the seat belt buzzer but otherwise they ate the same.
Bruce

Not for early seats. The passenger side is wider if I recall correctly in the fixed configuration.

thanks buddy

Yes for movable seats.
Some late passenger seats have a harness for the seat belt buzzer but otherwise they ate the same.
Bruce

They are interchangeable, but be aware the real left seat has an indentation on the left outboard side to provide clearance to work the park brake handle. It's not on the right seat. It will work, but you will hit your fingers on the seat when pulling the park brake.

I know this for a fact. I have to listen to complaints about broken fingernails all the time.