Curiouser, and curiouser! Well I have done a bit more research since my original post. It seems that I need the Gold Star tacho cable which is.........wait for it, wait for it, yep, it is 38 and 1/2 inches! More to the point, the BSA parts book is also wrong. The part number for an RGS tacho cable is 42-9227 and is described as being 2' 10 and a 1/2". That is way to short. The Gold Star cable is exactly the same length as the u/s cable that I removed from my bike which is a perfect fit. So you RGS owners out there, I would advise you to make a note for future reference. As luck would have it, I am probally the only RGS owner that did not know about this. It makes me wonder what other little booby traps are hidden away within the various parts book pages.