Hi guys
Just to confirm what some have already said re the rear Shock bolts..
The bolt sizes (Thread Pitch) on a 2015 GS are:
Upper Shock Bolt = M12 x 1.5 x 60mm
Lower shock Bolt = M12 x 1.75 x 75mm
The bolts are a 10.9 grade
I have found several UK bolt suppliers that can supply a 12.9 Grade bolt in those sizes if needed. The only difference is that they are Allen heads and not the BMW Torx type heads. (So what !!).