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#1 |
Registered User
![]() Join Date: Nov 2006
Location: KINGSPORT,TN.
Posts: 3,035
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12 bolt posi I.D. INFO HELP
I was going to swap the rear cover from a spare rear end onto my work truck ( 1971 12 bolt ) and when i removed the cover off my spare rear ( 1970 gmc w/leaf spring, 12 bolt ) the diff looks completely different than the open diff in my work truck. along with the cross pins for the spider gears it has 2 or 3 small pins that run between the carrier halfs and they have what looks like weights or something on them. is this a factory l/slip or posi . never seen one before. if it is i,am gonna swap it into my work truc 12 bolt. the rear covers are the same but the posi cover had a magnet from the factory on it inside. any help is appreciated. also if its a 3.08 gear ratio will my 3.73 gears work on it ?
bob Last edited by BCOWANWHEELS; 06-05-2007 at 08:20 PM. |
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#2 |
Active Member
Join Date: Oct 2006
Location: Ohio
Posts: 1,643
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Re: 12 bolt posi I.D. INFO HELP
Sounds like it is a posi unit.
3.08 will not interchange with 3.73 without a spaceror the use of aftermarket extra thick gears. If you swap it in make sue you buy the posi additive to go in your gear lube
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1968 SWB 454 + .040, 490HP x 540 FT pounds of Torque 10-1 Kb Forged pistons, recon rods w/ ARP wave loc bolts 781 heads Ported with 2.19/1.88 SSTvalves Lunati 60204 cam, Micro Trol lifters, Ported Edelbrock Performer Rpm manifold armor coated, Pertronix Triple Strike Ignition Holley 770 Street Avenger carb,Headers armor coated Built by Watson Ruppel Performance in Sarahsville Ohio. Hardshift Tranny Built Turbo 350,TSI 10" 3000 stall 12 Bolt Eaton Posi 4.10 Richmond Gears moser axles ![]() 18.5" x 31" Hoosier Pro Street Radials ![]() ET Classic 5 Wheels - polished Power Steering, Power Brakes,Disc Brakes,Tach & Gauge Dash, Tilt,Factory Air (gone) Custom Paint & Body Work Special thanks to my wife, my son and my money tree ![]() |
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#3 |
Join Date: Dec 1999
Location: Eastern - Manitoba Canada, Winnipeg
Posts: 4,369
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Re: 12 bolt posi I.D. INFO HELP
If it looks like a posi like this style, it's a gov-lock style, it will work until it goes ka-boom, not the recommended style for these older trucks.
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Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife. |
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#4 | |
Registered User
Join Date: Feb 2007
Location: Bend, OR
Posts: 110
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Re: 12 bolt posi I.D. INFO HELP
Quote:
A posi is going to have the side gears held by 2 plates and 4 heavy duty springs.
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'68 Chevy SWB with 460 BBC Muncie M-22 and Eaton posi rear w/ 3.73's Corvette rallys with mini derby caps Sick horsepower and torque |
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#5 |
Registered User
![]() Join Date: Nov 2006
Location: KINGSPORT,TN.
Posts: 3,035
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Re: 12 bolt posi I.D. INFO HELP
rod thats it .... think it will hold up on a stock 350 for highway use ? no hi-perf tire spinnin stuff, its just for my work truck. and lastly are they different for 3.08 and 3.73 gear sets ?
thanks bob |
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#6 |
Senior Member
Join Date: Feb 2005
Location: Maynardville, Tn
Posts: 3,030
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Re: 12 bolt posi I.D. INFO HELP
Bob, you can swap the gears, it will be a "3" series carrier.
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