yep this is the motor that I got from you Geof, one of these days I will go through it and it will go back into a 66 barracuda. So going by what you posted the B is for 66 273 motor and then 9-10 is September 10th thats what the block pad reads?
Yep, that's how it reads out!! Apparently, 273 motors were not selling very well, and maybe a lot of extra parts were hanging around waiting to be used! If this motor i have is any indication, they were just throwing them together at the end of 66!!