Further to Claude's discovery of finding a small B prefix of BFJ for the 1973 $1 banknotes, this prompted me to review the bundles of $1, I have received from my RBC branch in Eastern Ontario where 6 bundles of $1 banknotes were deposited as a collection dump. I was so focused on the BC series of prefixes due to the published existence of a small B prefix of BCL as stated in the Charlton Catalogue. Hence, I took another look and I found a $1 banknote with the small B prefix of BFG and please see the attachment for this banknote. I also included for reference the small BCP and small BCT prefixes which were posted earlier in this forum.
It appears that the small B prefixes for the 1973 $1 banknotes are less than 99.99% of the total production of approximately of 4,000,000,000 banknotes printed.
Please check your collections as you may have a "diamond in the rough".
Enjoy the search and pictures, Whitenite