In 1951, the R51/3 succeeded and modernized the 1950 R51/2, which was essentially a pre-war design that was produced after the war. The 600 cc R67, R67/2, and R67/3 series and the more sporting R68 model also followed the R51/2.
In 1951, the R51/3 improved upon and updated the 1950 R51/2, which was essentially a pre-war design that was produced after the war. The 600 cc R67, R67/2, and R67/3 series and the more sporting R68 model also followed in the footsteps of the R51/2.