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#1 |
Registered User
Join Date: Mar 2012
Location: manti utah
Posts: 67
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12 bolt rear end question
kay i just got a 12 bolt truck rear end out of a 1980 chevy k10, but it says it had the gt4 option on the rear end what does this mean?
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#2 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,455
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Re: 12 bolt rear end question
1980 would be a 10 bolt I think. But anyways GT4 is 3.73
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2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 6” lift 1999 GMC Yukon 350/4L60 4" SAS |
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#3 |
60-66 Nut
![]() ![]() Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,247
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Re: 12 bolt rear end question
I agree. The original rear differential in a 1980 K10 should be a 8.5" 10 bolt. The last year for the 12 bolt in the K series was '79. In the C series trucks they were available thru '82.
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#4 |
Registered User
Join Date: Mar 2012
Location: manti utah
Posts: 67
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Re: 12 bolt rear end question
weird this one is a 12 bolt out of an 1980 k10 lol i counted the bolts on the diff cover and it is a 12 bolt so i assume a 1980 12 bolt is pretty rare then and the vin on the receipt for the part does match for a 1980
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#5 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: 12 bolt rear end question
Through 1982 on the 12 bolt....some apps may have been 10 bolt, but 82 was the last yr on the 12 bolt ? My sources show me this, & yes it is a 3.73 gear.....but is it a "gov bomb" , or a good eaton clutch posi? Shoot a pic , if you can
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#6 |
60-66 Nut
![]() ![]() Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,247
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Re: 12 bolt rear end question
It could quite possibly be an early production 1980.
I don't have my RPO code list here, to look up what GT4 says, but I do know that the RPO code for a Gov-Lock is G80
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Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE |
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#7 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,455
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Re: 12 bolt rear end question
I know GT4 is 3.73, GT5 is 4.10, GU6 is 3.42, I can go on!!!!! G80 is the code for locking diff, but anything late 70s and up won't have the clutch type posi. Only G and I think they are B bodies (Caprice, Impala LeSabre) will have clutch type posi. I look all the time in junkyards for rears and posi's and such, scary, I even know some Ferd stuff.....But just do a google for RPO codes, probly half million of them out there...
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2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 6” lift 1999 GMC Yukon 350/4L60 4" SAS |
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#8 |
Registered User
Join Date: Aug 2011
Location: manti utah
Posts: 95
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Re: 12 bolt rear end question
it's not a posi lol it's a average run of the mill 12 bolt from the wrecking yard pulled from underneath a 1980 k10. the receipt i got from the wrecker gave me the vin number and i checked it and it conformed to a 1980 k10
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#9 |
78K & 79C Jimmys
Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
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Re: 12 bolt rear end question
my 79 Jimmy has RPO 1HE4 is a G80 and it's 3.4
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rear axle, rear end |
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