Be careful buying a front frame for a 500 for you 126 sun roof. I got one and apparently I only had to re-profile it a bit and it was supposed to do the trick ( flatter curve to the roof line than a 500) it worked up to the point of locking but would not stay latched into the over-centre position, so I had to hold it shut with a piece of locking wire! In the end I dug out my old rusty 126 frame, refurbished it and fitted it back on the car, no more problems.