There were certainly 2 versions of the 1960-63 parts book, the later version including some changes up to frame GA7 11101 which started the 1961 model season and the earlier version not including the Triumph type 4 spring clutch.
To cope with modifications to parts and new parts introduced BSA issued unillustrated Parts Service Bulletins to dealers giving details. These were issued in series prefix GA for the twins, GB for B group singles. GC for C15, GD for Bantam, G for all models, N for new parts......... there were a lot of them issued.
So our parts books may not show a complete picture.
Dealers/storemen would use them to ammend their books.
The most famous of these parts bulletins probably being G21 from April 1962 which listed RGS parts and N8 from August 1963 which list late Super Rocket and RGS parts (plus some A50 and A65 parts)
Below are 2 bulletins showing the general layout.