Installing posi / Spline count

[MAQ's72]

Hey Guy's

I searched in the drivetrain forum but could not find my answer.

 

Anybody know what the standard spline could would be for my 72 with a 12 bolt rear end from Factory? She came with a 350/4V It has the 2.73 open diff as it came off the line I am fairly sure. I like to buy a posi unit like an Eaton with a 3 carrier to go to a 3:55 or 3.33 but the specs on the Eaton comes in different spline configurations..ie: 30 or 33 or 28 any Idea of the ones I would or should have in it without pulling the axles 

[MC1of80]

All the stock a-body 12 bolt rears that I have / have had all had 30 spline axles from the factory.

[dejh22]

Just had new carrier and gears put in a 1972 and 1971 Monte Carlo. Both had stock 12 bolt rears with 273 gears. Both were 30 spline axles. I believe 10 bolt rears are 28 spline.

[MAQ's72]

Hey Guys,

thanks for that info, yes it should be a 30 spline axle as I found this great page online to confirm... what you both said.... 30 spline for sure

 

This below is real useful..