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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 79brent on May 08, 2013, 05:00:00 pm

Title: 2.76 and 2.73 rear axle ratio
Post by: 79brent on May 08, 2013, 05:00:00 pm
OK so I have a 1979 Chevy shortbed that came factory with a 2.76 ratio(according to the factory paper build sheet and the glove box laminated sheet). Did they change the ratio for the 81-87 or something? I always see people saying 2.73. Just a random question that has me curios.
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: zieg85 on May 08, 2013, 06:10:26 pm
I have never seen a "GM" 2.76 ratio, but that is just me.
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: 79brent on May 08, 2013, 07:18:07 pm
Im 99% sure that's what it says. Ill take a picture of it if it does say that. Always had me wondering.
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: zieg85 on May 08, 2013, 07:52:16 pm
Quote from: 79brent on May 08, 2013, 07:18:07 pm
Im 99% sure that's what it says. Ill take a picture of it if it does say that. Always had me wondering.

Sorry about the mis-information...  I did find a 2.76 in the RPO codes...
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: 79brent on May 09, 2013, 09:09:26 am
Its all good. Don't know what they would chant to go from 2.76 to 2.73. Probably just changed the numbers. Option HC2 I have pictures but they are to large to upload.  :o
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: Stewart G Griffin on May 09, 2013, 12:15:16 pm
Is this 1/2, 3/4 or 1 ton?
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: 79brent on May 09, 2013, 01:53:28 pm
It is my 1/2 ton, the one in the picture. I'm about to swap out those "dog" gears for a 3.73 limited slip off of a 88 chevy longbed, just gotta move the spring perches in a little bit. I've haven't heard of many people with this axle ratio.
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: zieg85 on May 09, 2013, 02:02:43 pm
Quote from: 79brent on May 09, 2013, 09:09:26 am
Its all good. Don't know what they would chant to go from 2.76 to 2.73. Probably just changed the numbers. Option HC2 I have pictures but they are to large to upload.  :o

I think the difference is between the 12 bolt 2.76 and the 10 bolt 2.73 in the 1/2 ton pickups
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: 79brent on May 09, 2013, 02:12:20 pm
Your probably right Zieg. Is there anything bad about the 10 bolt vs the 12 bolt? The 3.73 I have for it is a 10 bolt. I heard the only real difference is .25" in ring gear size. I plan on getting that swapped in once I get the perches moved and the proper U bolts for it.
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: zieg85 on May 09, 2013, 02:31:55 pm
Quote from: 79brent on May 09, 2013, 02:12:20 pm
Your probably right Zieg. Is there anything bad about the 10 bolt vs the 12 bolt? The 3.73 I have for it is a 10 bolt. I heard the only real difference is .25" in ring gear size. I plan on getting that swapped in once I get the perches moved and the proper U bolts for it.

I have heard both the 10 and 12 bolt are comparable in the GM truck rear ends.  I have never had anything powerful to break one as all mine have been pretty much stock slug engines...
Title: Re: 2.76 and 2.73 rear axle ratio
Post by: 79brent on May 09, 2013, 02:46:49 pm
yeah I got a bone stock motor right now in it. Once im able to save up some money I will build but wont go beyong the breaking point of the axle ever.