55-64 Chevy gear ratio ?

DZauto is the guru on 58 to 64 chev rearends you can find him at chevytalk
Tri-Five housings/axles. - ChevyTalk --The Social Network for Chevy Fans

 

We have a 59 Impala 283/PG car that came factory with the 3.36 rear. Swapped it out for the with a 348/PG center section that had 3.08s.

 

Looking for some help identifying stamping numbers on 55-64 rear axle carrier units
There appears to be 2 sets of numbers one appears to be a date the other could also be a date
Anybody know how or have a chart to decode
See Pictures (sorry for the duplication)

Thanks