12bolt questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tom · 06-04-2003, 05:21 PM

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

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

06-04-2003, 05:21 PM	#1
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,701	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! __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

06-04-2003, 07:20 PM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	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. __________________ Mike 1985 Chevy C-10

06-04-2003, 11:10 PM	#3
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,701	thanks mike. BTW, whats the OAC? __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

06-05-2003, 03:59 AM	#5
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	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. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

06-04-2003, 11:17 PM	#4
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,826	i says "OFC" I believe it means old farts club. ...Jeff



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