1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
They just hook on. No fasteners. It's been a lot of years since I had mine out but it seems that the seat back hooks and slides down slightly. The seat bottom installs rear end first and the front is then pushed down behind the adjuster lever and snaps in place. If you don't see what I'm talking about when looking at yours I'll pull mine out and take a picture or two.
Thanks for that , it was hard for me to see how they held on for the frames and seats were out of the car and I was not sure if they were matching.You see its a full resto and the car I purchased was not well assembled when I got it.
Thanks again Jose