hi, im rebuilding a jdm h22a and was wondering if anyone on here could shed some light on the serial number?

there are a few numbers cast into the block front just below the deck. on the left hand side the numbers read 12 5 1. on the right hand side it reads no.2 91.

the serial number itself is 1010751, stamped directly below the h22a.

i know that h22a relates to it being a jdm motor, im guessing the no.2 91 means it was cast in 1991 on production line 2?

any info would be appreciated