Strike 1 and 2...
The regulator looks original and is still riveted in place.
I did the rear track before on the Drivers side. So I checked that bolt and it was there on the operator side... also it is a lot longer than 10mm.
On Realoem it shows there are 6 og these bolts used somewhere in the door. See item 23. By the way, what is item 21? Any other ideas?
http://www.realoem.com/bmw/showparts...55&hg=51&fg=10