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07-15-2025, 01:11 PM
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#1 |
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Registered User
Join Date: May 2016
Location: Salisbury, MD
Posts: 63
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My HO72 Questions
I have a 1972 HO72 under my truck. I'm trying to figure out if it's a posi or limited slip or locker or what.
Rear axle on jackstands, transmission in Park, I can rotate rear wheels without the driveshaft turning. When I turn one side the other wheel turns in the opposite direction. Never does one wheel stay still when turning the other. What do I have here? Thanks! |
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07-15-2025, 01:59 PM
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#2 |
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Senior Member
 
Join Date: Dec 2022
Location: Peoria, Arizona
Posts: 684
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Re: My HO72 Questions
If one side is spinning in one direction and the other in the reverse direction, you have an open differential.
Clay
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Clayton Sikes Peoria, Arizona 1967 Chevy K20 "The Town Truck" Build Thread: https://67-72chevytrucks.com/vboard/...d.php?t=841272 |
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07-15-2025, 06:26 PM
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#3 | |
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Proprietor of Dale's Corner
Join Date: Nov 2012
Location: Vacaville , CA
Posts: 16,866
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Re: My HO72 Questions
Quote:
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"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man R.I.P. FleetsidePaul |
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07-16-2025, 12:36 AM
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#4 | |
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20' Daredevil (Ret)
Join Date: May 2003
Location: Jefferson State
Posts: 14,020
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Re: My HO72 Questions
Quote:
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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07-16-2025, 09:13 AM
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#5 |
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Registered User
Join Date: Feb 2000
Location: Maquoketa, Ia/ Orr, Mn
Posts: 3,257
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Re: My HO72 Questions
The code stamped on the top of the cast differential housing will tell you if it was built with a no-spin or open differential. It should be three letters followed by the build date.
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'51 South Bend Model "9A" '56 Chevy 3600 NAPCO '74 Chevy Cheyenne Super K20-restored on 37's '72 GMC Sierra Custom K2500- in progress '08 GMC Envoy Denali '12 GMC Sierra 2500HD Denali '17 GMC Yukon XL VCCA member #58596 http://www.nohrco.com |
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07-16-2025, 11:49 PM
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#6 |
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Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,790
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Re: My HO72 Questions
The only option for the HO rear was the maximum traction or Detroit Locker. There were no “Positraction” type limited slips available. So like the other posters said, if you rotate one and the other goes opposite, open diff. Rotate one and other goes same way, locked.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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