Rear chain 110056, 530, (5/8 inch x 3/8 inch, 0.625 in x 0.380 in) 99 pitch Renolds A&S with joinerSuit Norton Commando 1968 - 72 [21T gearbox sprocket]; 1973 -1975 850 MkI, MkII, Mk1A, MKIIA. MkIIIAR10B1