I have a 12 bolt carrier which I thought was a 2 series. Then I opened the April issue of Car Craft (which has turned into a great mag) only to find that my carrier looks nothing like the 2 series but is identical to the 3 series they have pictured. I know that common sense would say that I have a 3 series, but I don't want to spend any $$ on it until I'm sure of what I have.

I know that if you stand the carriers on end, there is a measurable height difference between them.

Does anyone know the height of the carriers? Or does anyone know of a way to distinguish between a 2,3,& 4 series carrier?

I just read that article on 12 bolts, If you look at the 3 carriers's they are backwards. The 4 seires is the shortest because the pinon on a 4 seires is smaller in diameter and that makes the ring gear closer to the center line of the carrier. And in the case of the 2 seires the pinon is larger in diameter and that makes the ring gear move father up the carrier. that why if you put a 4 seires ring gear on a 3 seires carrier you need the spacer to move the ring gear closer to the center line because the diameter of the pinon is smaller. Watch those articles they screw up some times.

The casting numbers on a 12 bolt posi CASE(Not the housing!) are as follows:
2 Series:ED32088 Gears 2.73:1 and down
3 Series:30140PM1 Gears 3.08 to 3.73:1
4 Series:EDB32298 Gears 3.90:1 and up

Tom,

Now THAT was the information that I was looking for.

I owe ya a beer.