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#1 |
Registered User
Join Date: Aug 2011
Location: manti utah
Posts: 95
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1978 k10 rear end gone out
i have a 12 bolt rear end under it and it went out. how hard would it be to find and swap it for a posi and would it be worth it? idk what gear ratio mine is as its missing the tag any tips to find out
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#2 |
Registered User
Join Date: Aug 2011
Location: manti utah
Posts: 95
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Re: 1978 k10 rear end gone out
bump anyone know?
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#3 |
Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: 1978 k10 rear end gone out
You can go to any pull apart and just swap in a ten bolt 8.5 the pinion shaft is stronger than the truck twelve.
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377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511 |
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#4 |
Registered User
Join Date: Feb 2007
Location: Austin, TX
Posts: 3,930
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Re: 1978 k10 rear end gone out
Look on the glove box and see if there is a gear ratio listed. If not, you will need to pull the rear diff cover and count teeth. Teeth on ring gear divided by teeth on pinion is your gear ratio.
Depending what happened to your rear end will decide how much it will cost to fix. From there you can add a posi or whatever else you'd like. See how far gone it is, sometimes a rebuild comes out better than a junkyard axle and you are starting with fresh parts. The other option is to grab a junkyard axle with the same ratio. Pull the cover, make sure it's looks good and hope for the best.
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1977 GMC Sierra Grande Last edited by Pyrotechnic; 10-29-2012 at 09:17 PM. |
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#5 | |
Registered User
Join Date: Feb 2007
Location: Austin, TX
Posts: 3,930
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Re: 1978 k10 rear end gone out
Quote:
Yes, it is true that the 8.5 10 bolt has a larger pinion shaft than the truck 12 bolt. However, the Ford 9 inch has a pinion shaft even smaller than the truck 12 bolt. It's really a draw as to which design is better, but either one is a decent choice stock and both can be made very strong with aftermarket parts. Also, if you swap to a 10 bolt, you will need a have the rear U joint changed on the driveshaft to a conversion joint. Something to keep in mind when adding up costs.
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1977 GMC Sierra Grande Last edited by Pyrotechnic; 10-29-2012 at 09:22 PM. |
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#6 |
78K & 79C Jimmys
Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
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Re: 1978 k10 rear end gone out
I think my 79 12 bolt was stamped front of axle on drivers side of pumpkin?
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John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350 |
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#7 | |
Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: 1978 k10 rear end gone out
Quote:
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377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511 |
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#8 |
Registered User
Join Date: Aug 2011
Location: manti utah
Posts: 95
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Re: 1978 k10 rear end gone out
it us a 373 12 bolt have not had enough too replace it yet .
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#9 |
Suburban Hick
![]() Join Date: Aug 2008
Location: Altoona, IA
Posts: 810
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Re: 1978 k10 rear end gone out
Mine just went out in my 78 k10 as well. I don't ever plan on getting rid of it but i priced out what it would cost to rebuild it. I figured if I had to go through the trouble of replacing the ring and pinion I might as well go through the entire axle. Mine was a factory posi and I wanted to replace a posi with a posi. After I added up all the costs it was going to be around $800 to rebuild the rear end with quality products and a good locker. I just couldn't see spending that kind of money on the old girl at the moment so i put a wtb ad on craigslist. I bought a factory pozi 10 bolt for $200 with 50000 miles. I also bought an unknown set of axles for $50. The main thing to check is the play between gears and to make sure the pinion is tight. Either way you should rebuild the brakes on a used axle. Just my 2 cents hope it helps.
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Mathew 1947 Chevy 3600 1951 GMC 100 1969 Chevy C-10 396/500hp TH400 lowered 4" 1968 Imapla Custom 396/325hp TH400 "Grandmas Car" 1976 Crew Cab 4x4 diesel http://67-72chevytrucks.com/vboard/s...d.php?t=488505 1978 Chevy K-10 454 1983 S10 4x4 "Bumblb" (Grandpa's truck) 1993 Chevy S10 V8 conversion 1990 Ford Probe Gt 1992 Dodge W-150 "Old Man's Truck" 1992 Pontiac Grand Prix SE 1992 Mercury Grand Marquis-Mercruiser 2000 Ford F150 (Currently my mother drives this) 1946 Farmall H with Stan Hoist loader 1965 John Deere 110 1961 Wheel Horse " Rat Tractor" |
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#10 |
Registered User
Join Date: Aug 2011
Location: manti utah
Posts: 95
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Re: 1978 k10 rear end gone out
I do not plan on gettin rid of mine either took me near a year of dishwashing too save up the grand to get it. The brakes on my current rear are still great il swap parts whenever I get the bread to get another differential
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#11 |
Registered User
Join Date: Nov 2010
Location: Windsor Locks
Posts: 628
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Re: 1978 k10 rear end gone out
I rebuilt a junkyard 12 bolt last year after an accident broke my original. I was about 1200 bucks in with the junkyard axle, a new eaton posi, motive gears, setup/bearing kit, wheel bearings, and brake parts. looking back on it I wish I would have picked up a 6 lug 14 bolt and built that instead.
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#12 | |
just can't cover up my redneck
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
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Re: 1978 k10 rear end gone out
6 lug 14 bolts are still just a semi-floating axle. Is it really that much better?
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#13 |
Registered User
Join Date: Nov 2010
Location: Windsor Locks
Posts: 628
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Re: 1978 k10 rear end gone out
Everything is bigger in it, but same problem as a 10 or 12 bolt if you break an axle shaft.
I wasn't really looking to buy another set of wheels at the time and swap the front dana 44 parts to 8 lug stuff to match. It depends what the truck is used for whether or not its worth it I guess |
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