what do u mean but 2nd and 3rd series carrier and how do i find out which i have

 

Snowman in your 2.77 ratio 9 bolt you have a 2 series carrier. I just learned all about this myself recently but as I understand it, GM made their rears with different size carriers (Posi unit) So as they made different ratio's the ring gear would have the same thickness and strength. If they made the same size carrier (which ford does) The ring gear would get thicker or thinner in order to contact the pinion gear. Which means if it gets thinner it will lose its strength. If anyone else can explain this better please do. Like I said I am just learning this myself