I worked on the inside skins today. The factory have the seat belts running between the skin and the canopy. If I riveted the skins the seat belt would not run freely. My aircraft is an early model and the later aircraft has a recess in the canopy to allow the seat belt to retract After alot of experimenting I decided to modify the skins to allow the seat belts to run freely. The upholstery will cover my cutouts and I am much happier with this modification.