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- - 12bolt questions (https://67-72chevytrucks.com/vboard/showthread.php?t=55416)

Tom	06-04-2003 05:21 PM

12bolt questions

Hey guys I need some info on the 12bolts that came in our trucks. First off, I know there is a series 3 and a series 4 carrier. Which carrier holds which gears? Second, how many splines are stock? Thanks!

swervin ervin

06-04-2003 07:20 PM

They are 30 splines. A 3 series goes up to 3.73, and a 4 series is needed for 3.73 up. Although, I think you can buy aftermarket
3.73 and lower gears for a 3 series carrier.

Tom	06-04-2003 11:10 PM

thanks mike. BTW, whats the OAC?

bigblock73

06-04-2003 11:17 PM

i says "OFC"

I believe it means old farts club.

...Jeff

79BIG10

06-05-2003 03:59 AM

Tom if you want to keep your present carrier say series 3 and want to go up to a 3.73 there are companies that make thicker gears to accomodate a 3.73 in a series 4 carrier.

Tom	06-05-2003 01:22 PM

Quote:

Originally posted by bigblock73
i says "OFC"

LOL! correcting me and messing up yourself! Classic :D

Im pretty sure I have a series 3 carrier then. Im going to 4.10's with a spool. Hopfully theres a company that can help. Thanks guys ;)

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