Hi trevinoz. It seems that you could be correct, I have rechecked the BSA parts listing for 1954/55 Swinging arm A7/A10 and they do seem to have just the one bearing retaining nut on the spline side of the hub. This appears to be the same for Gold Stars, so that seems to answer the question, but, my early A7SS project that I checked, now seems to have a plunger hub fitted (with 2 bearing retaining nuts) so I can swop the hubs over. This leads me onto another question. The flush rivets in the swinging arm hub are just showing signs of being loose, so does anybody know of a method/source of rivets to rectify this without resorting to the cost of an SRM exchange hub? any info greatfully received. Regards, Peter