*early* '68 Z28 4053 carb date code

[69Z28-RS]

There is a 4053 carb on ebay right now, with a date code of '705'.       The seller says it represents a date of 5th week of October 1967. 
Is that accurate?    How were Nov 67 carbs dated? and Dec?   
Was there a change in the month part of the code designation somewhere along the line between '67 and '69?   

[1968RSZ28]

http://www.camaros.org/carb.shtml#holl

Paul