That's interesting info, Andy.
Were there any A65s with A50C frame numbers that late, or just the A50s?
There is scope for endless distraction in those dispatch records.
i read some where , probably right here on BritBike
that #3217 is the first matching number 650 recorded in the dispatch books .
( still searching for the quote )
does the first matching mean the last non matching ? ... i would think so , but you never know
1966 was very messy year for BSA .
4000 twins were shipped from the US , back the the UK ... to have various problems remedied .