The Y-A block is kinda cool. The last $1 SC printed was the 1957B Y12480000A, so yours is towards the very end. I don’t believe that or being consecutive makes much of a difference on value.
I believe that the runs are printed in reverse order, that is the lower serial numbers would be the last ones printed. This makes the straps easy to assemble from lowest to highest serial numbers. So the Y12480000A would have been printed at the beginning of the run. Is this correct or do I have my facts backwards?
It for sure adds to the cool factor, however the 1957 Series is one of the Most produced S.C , even the *STARS* in crisp unc condition are only worth about $20.