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09-05-2019, 08:11 PM
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#1 |
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Registered User
Join Date: Feb 2015
Location: Seattle
Posts: 14
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Identifying rear diff on 1980 C20. LSD or not?
My truck has a 14-bolt rear differential. I've removed the cover and drained the oil, and am about ready to button it all back up and refill with fresh oil. However, I can't figure out if this truck has an LSD or not, and therefore whether to add LSD additive into the oil.
Picture: https://imgur.com/VLqjWER With the rear end jacked up, and transmission in neutral, when I spin one wheel, the other stays stationary. But if I put in gear and spin one wheel, the other spins the other way. I'm inclined to think this means it does NOT have an LSD, but I'm getting so much conflicting information after searching extensively that I am not feeling very confident about this. Help? |
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09-05-2019, 08:45 PM
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#2 |
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Moderator
 
Join Date: Jun 2017
Location: Cherryville, NC
Posts: 2,204
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Re: Identifying rear diff on 1980 C20. LSD or not?
The diff described and pictured is not an LSD...it is an open or standard diff...
__________________
Family and country before all others... 2006 Chevy Silverado (Daily Driver) 2012 Chevy Equinox 
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09-05-2019, 09:21 PM
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#3 |
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Registered User
Join Date: May 2012
Location: horseheads,ny rust belt
Posts: 2,794
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Re: Identifying rear diff on 1980 C20. LSD or not?
4 windows and see spider gears = open
4 windows and see coil spring and block of steel = detroit locker ........... do NOT pull apart a detroit type unit unless you bolt the unit together inside or it will pop open good on you and might hurt . 3 pins on the center of case were the ring gear bolts and no windows = gov-loc posi unit . 3 pics in order as i typed above .
__________________
77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great. |
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09-05-2019, 09:46 PM
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#4 |
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Post Whore
 
Join Date: May 2015
Location: Alabama
Posts: 14,670
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Re: Identifying rear diff on 1980 C20. LSD or not?
("3 pins on the center of case were the ring gear bolts and no windows = gov-loc posi unit .")
what k30 posted is what you have.....G80 it is not a open diff..it the GM version of a posi
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
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09-06-2019, 10:18 AM
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#5 |
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Registered User
Join Date: May 2012
Location: horseheads,ny rust belt
Posts: 2,794
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Re: Identifying rear diff on 1980 C20. LSD or not?
forgot to add also . the strongest of the gov-loc posi units is the 14ff . i have run them stock to built 400 sbc engines with 38" tall super swamper mud tires and no problems .
__________________
77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great. |
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09-06-2019, 03:12 PM
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#6 | |
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Registered User
Join Date: Feb 2015
Location: Seattle
Posts: 14
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Re: Identifying rear diff on 1980 C20. LSD or not?
Quote:
Here's a better pic, you can see one of the windows and small gears: https://imgur.com/a/7u0Z6Hv |
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09-06-2019, 04:52 PM
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#7 |
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Post Whore
Join Date: May 2015
Location: Alabama
Posts: 14,670
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Re: Identifying rear diff on 1980 C20. LSD or not?
I think i see the windows now...so that changes my opinion...couldn't see them in the other pic...looks open
__________________
Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
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09-06-2019, 05:49 PM
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#8 |
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Registered User
Join Date: May 2012
Location: horseheads,ny rust belt
Posts: 2,794
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Re: Identifying rear diff on 1980 C20. LSD or not?
open diff or gov-lov both call for std gear oil in these axles .
and yes you have open diff .
__________________
77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great. |
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