Axle code question

I was on woodys fairlane site and tried to use his axle code identifier, but mine is not on there, i just got this 67 fairlane 500, and the axle code is 0 or O i dont know which but neither are on the list of choices, wondering if anyone knew what it ment

that is a 3.10 to 1

not to sound stuppid but open or locking, i havnt had the time to check its just sat in my driveway for 4 days
thanks for the help so far

Historically, codes that are numeric are open, Letters are locking... Look at the tag on the dif itself... a 3L10 would be a locking rear, while 3.10 would not.... HTH