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Old 01-01-2013, 05:05 PM
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grand national 8.5 ' gears '

Are their any interchangeable gears that would fit a grand national 8.5 ?

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Old 01-01-2013, 05:40 PM
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Yes, there are a lot of gears that will fit that rear end. It's the corporate 8.5 that was used in many GM cars and trucks from '71 and up. There are gear ratios from 2.41 to 5.13 for the 8.5. You can also upgrade it from 28 spline to 30 spline axles with a 30 spline Eaton Posi and after market axles.
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Old 01-01-2013, 08:03 PM
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I'm just looking for a 3:42
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Old 01-01-2013, 08:06 PM
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That's the most comon gear for the 8.5. They were installed in about a million GM 1/2 ton trucks from '81 up and many second gen Z28s.
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Old 01-01-2013, 08:31 PM
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What's the easiest car too find
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Old 01-01-2013, 09:49 PM
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I'm just looking for a 3:42
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Old 01-02-2013, 05:53 AM
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GM 1/2 ton trucks with the GU6 code from '82 and up.
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Old 01-02-2013, 01:28 PM
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what gear in it now??
if the g.n was pre 2004r it might be 342
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Old 01-03-2013, 06:03 PM
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I got the rear end from a Guy he said it was a 390
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Old 01-05-2013, 03:09 PM
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Quote:
Originally Posted by sscanrun View Post
I got the rear end from a Guy he said it was a 390
did you take the cover off and count the teeth or look for the stamp that would tell you, or turn the drum and count the yoke revolutions?

You could already have 3.42 and not know it.
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