727 identification numbers

I want to buy a rebuild kit for a 727 but they ask if it pre-71' or after 71' I don't what year it is. it the first set of #'s... the 2nd set? or the 3rd set, or all of them together? Is there a place where I can check on-line to see when it was built? First Trans is PK3681053 then a pause 4221 then a pause 9910. the second transmission is 3515841 then a pause 3496 then a pause 9969. I'm not sure which one I should rebuild. And I dont wanna buy the wrong kit. any help would greatly appreciated.