Appropriately late to the party with my model 66s'.
These 3 inchers range from -2 AFK prefix -3 BBT prefix -4 CAT prefix and the 2 -5s' ,,
Thanks to Chris (SnW357) for the model 66-3 to fill in the set!
The barrel profiles of the various model 66s' and a 4" 65-6.
A 66-5 4" round butt ,when found ,very serviceable guns.
Regards ,, Allen Frame