I have a convertible and the seat tensioners where damaged. I removed them and got a pair of universal 3 point seat belts. I installed the tensioner at the top inside the rear quarter panel, had to lift it up with a piece of metal. After all it was one of the best mods I made on the car. Cheap, easy and functional. Installation was very easy, even better then OEM and on the floor is not tensioner anymore
I made some photos, hope you can see something on them. It is a convertible and behind the rear quarter panel cover is the tensioner roll. I had to out a square metal 2x2 under it, used longer bolts and thats all. Overall easy installation