What rear end gearing do I have? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

xtreme80 · 02-04-2007, 11:05 PM

My truck is a 1980, came from the factory with a 350-4bbl/TH350. It's got a 12 bolt rear end, not sure if that's original though.

How would I find out what gears I have in the back?

Srubydo1986 · 02-04-2007, 11:52 PM

look in the glove box it should still have a paper tag telling you if not beats me also i think it might be on the driver door

**Captkaos** · 02-05-2007, 06:00 PM

If it is anything but standard it will be listed in the glove box in the RPO section, if it is standard, it is most likely 3.08. There is a stamping on the axle, but I don't have the codes to decifer them...

msgross · 02-05-2007, 06:10 PM

I have the codes for the ring gear numbers but you have to take the cover off....

**Captkaos** · 02-05-2007, 06:31 PM

If you get in that deep you can just read them off the ring gear and divide them to get the ratio.

xtreme80 · 02-05-2007, 08:43 PM

I'll just look at the RPO sheet. I don't think the 12 bolt came on the truck from the factory, but I'll just assume that it did!

Srubydo1986 · 02-05-2007, 10:42 PM

from what i was told the 2500 2wd did have a 6 lug 12 bolts but i think it was in a later models not our years

msgross · 02-05-2007, 11:10 PM

my 68 4wd has 12 bolt with 3.73's

**Captkaos** · 02-06-2007, 12:00 AM

Quote:

Originally Posted by xtreme80

I'll just look at the RPO sheet. I don't think the 12 bolt came on the truck from the factory, but I'll just assume that it did!

12bolts came factory on all 73-80's. 10bolts started showing up in 81 and 12bolts were gone by 82...

xtreme80 · 02-06-2007, 01:50 AM

Quote:

Originally Posted by Captkaos

12bolts came factory on all 73-80's. 10bolts started showing up in 81 and 12bolts were gone by 82...

Oh! Then I'll look at the RPO sheet tomorrow and find out! Thanks!

02-04-2007, 11:05 PM	#1
xtreme80 Wishin' I had more money! Join Date: Feb 2007 Location: Eugene, OR Posts: 1,242	What rear end gearing do I have? My truck is a 1980, came from the factory with a 350-4bbl/TH350. It's got a 12 bolt rear end, not sure if that's original though. How would I find out what gears I have in the back?

02-04-2007, 11:52 PM	#2
Srubydo1986 The Crazy Machanic Join Date: Jan 2007 Location: Nokesville Va Posts: 1,437	Re: What rear end gearing do I have? look in the glove box it should still have a paper tag telling you if not beats me also i think it might be on the driver door Last edited by Srubydo1986; 02-05-2007 at 12:21 AM.

02-05-2007, 06:00 PM	#3
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: What rear end gearing do I have? If it is anything but standard it will be listed in the glove box in the RPO section, if it is standard, it is most likely 3.08. There is a stamping on the axle, but I don't have the codes to decifer them... __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

02-05-2007, 06:10 PM	#4
msgross Registered User Join Date: Jul 2006 Location: Central PA Posts: 12,201	Re: What rear end gearing do I have? I have the codes for the ring gear numbers but you have to take the cover off.... __________________ The Garage: 1968 K-10 SWB - "Project Money Pit" 1996 Z-71 - "huntin rig" 1969 C-10 LWB (SOLD) "Project flip that truck or else" 1993 Passport, F@rd 1-ton (SOLD)"Project Cousin Eddie" My Garage Build "The 1,000 footer"

02-05-2007, 06:31 PM	#5
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: What rear end gearing do I have? If you get in that deep you can just read them off the ring gear and divide them to get the ratio. __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

02-05-2007, 08:43 PM	#6
xtreme80 Wishin' I had more money! Join Date: Feb 2007 Location: Eugene, OR Posts: 1,242	Re: What rear end gearing do I have? I'll just look at the RPO sheet. I don't think the 12 bolt came on the truck from the factory, but I'll just assume that it did!

02-05-2007, 10:42 PM	#7
Srubydo1986 The Crazy Machanic Join Date: Jan 2007 Location: Nokesville Va Posts: 1,437	Re: What rear end gearing do I have? from what i was told the 2500 2wd did have a 6 lug 12 bolts but i think it was in a later models not our years

02-05-2007, 11:10 PM	#8
msgross Registered User Join Date: Jul 2006 Location: Central PA Posts: 12,201	Re: What rear end gearing do I have? my 68 4wd has 12 bolt with 3.73's __________________ The Garage: 1968 K-10 SWB - "Project Money Pit" 1996 Z-71 - "huntin rig" 1969 C-10 LWB (SOLD) "Project flip that truck or else" 1993 Passport, F@rd 1-ton (SOLD)"Project Cousin Eddie" My Garage Build "The 1,000 footer" Last edited by msgross; 02-05-2007 at 11:10 PM.



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