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Rear end differential mystery

How do I go about buying a posi diff.

Rear end differential mystery

Postby Killain [OP] » Feb 22 2013, 9:58pm

I'm trying to buy and install a posi-trac differential in my 1990 Chevy 1500 Silverado, it's got a 305 ci. V8 and a 700R4 and the gears back there are 3:42. Can anyone tell me how to go about figuring out if I have a 28 or a 30 spline rear end ? I called a couple of dealers, but they all say the truck is too old to look up any information on. Any ideas are more than welcome. I can buy a brand new Eaton posi-trac for about $450.00 but I need to know what number of splines it has. Thank you !
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1990 Chevy Pickup 1.20.2013 PICTURES 003.JPG
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Killain
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Related Topics  Groan from front end differential?   Rear differential went out   new rear differential   locking rear differential   Rear Differential Clatter   rear differential noise trouble   Front and Rear Differential Gaskets   2007 4.8 2WD 3.23 rear differential   rear differential lube capacity   Changing rear differential oil   Problem After Rear Differential Fluid Change   Are rear end gears the same as front end gears on a 10 bolt   New rear end????   Rear end gears 
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Re: Rear end differential mystery

Postby steved » Feb 22 2013, 10:11pm

Call Randy's Ring and Pinion, they should be able to tell you...
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Re: Rear end differential mystery

Postby Killain [OP] » Feb 25 2013, 10:25pm

How do I contact them ? Thank you !
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Re: Rear end differential mystery

Postby 19trax95 » Feb 25 2013, 10:32pm

Off topic but....

Thats a pretty clean looking obs you got there.
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Re: Rear end differential mystery

Postby Killain [OP] » Feb 25 2013, 10:58pm

Whats an OBS ?
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Re: Rear end differential mystery

Postby 19trax95 » Feb 25 2013, 11:09pm

Obs is just an acronym for old body style. Which encompasses model year 1988-1998. Then there is oobs (old old body style) which is 72-87. Nbs is 99-07.5 and nnbs is 07.5-2013
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Re: Rear end differential mystery

Postby Daly » Feb 25 2013, 11:18pm

In 1990 they were 30 spline. And +1 on the truck, it is a beautiful looking truck.

I do hate the acronyms for trucks. People should get use to calling them by there GM names, at least from 88 on.
88-98 GMT400
99-07 GMT800
07.5-13 GMT900
What are they going to call the 2014's, NNNBS (new new new body style) It's stupid IMO.
2014 Silverado LT…
Daly's 2014 Silverado
2012 Silverado LS - gone
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Re: Rear end differential mystery

Postby Killain [OP] » Feb 26 2013, 1:11am

Well then, Thank you very much. I've wanted to install a Posi-trac differential and I have found a few, prices are all about the same $425.00 New, but I didn't know what splines I needed. Thank you. And yes, It is a great looking truck, which took a lot of sweat equity to get to where it is. Thank you for your help !
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Re: Rear end differential mystery

Postby steved » Feb 26 2013, 3:28am

Randy's Ring and Pinion should have a website. There is also 4xHeaven, which is a little mom and pop type store, but they always treated me well and gave good prices.
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Re: Rear end differential mystery

Postby Killain [OP] » Feb 26 2013, 10:48am

Thank you !
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Extra Info: 305 V8 5.0 liter
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