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Old 10-04-2012, 12:25 PM   #1
Tomahawk30
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K20 Gear Ratio Question

Anybody know the standard gear ratio for a 72 K20 w/ auto transmission? It seems pretty low-geared on the highway, and I'm thinking I may want to swap the gears out for something a little more highway friendly. Any suggestions on a replacement ratio?
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Old 10-04-2012, 03:19 PM   #2
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Re: K20 Gear Ratio Question

4.10
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Old 10-04-2012, 04:03 PM   #3
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Re: K20 Gear Ratio Question

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Originally Posted by SS Tim View Post
4.10
Thanks Tim! That answers my same question regarding my K20 with a 4 spd....
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Old 10-04-2012, 04:55 PM   #4
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Re: K20 Gear Ratio Question

Cool, thanks Tim! That's what I was thinking it was supposed to be, but I couldn't find the verification anywhere.
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Old 10-04-2012, 09:44 PM   #5
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Re: K20 Gear Ratio Question

That's the tallest gears you get with that rear.
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Old 10-04-2012, 09:54 PM   #6
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Re: K20 Gear Ratio Question

Unless he has a Dana 60.
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Old 10-04-2012, 10:10 PM   #7
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Re: K20 Gear Ratio Question

A Dana 60 stock on a '72 K20 ?????
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Old 10-04-2012, 11:04 PM   #8
Tomahawk30
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Re: K20 Gear Ratio Question

Nope, its the round cover GM 10 bolt rear end. I'll probably just get used to them. I have the 70 2wd C10 that I'll probably do the bulk of my highway driving in anyway!
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Old 10-04-2012, 11:06 PM   #9
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Re: K20 Gear Ratio Question

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Originally Posted by 1972RedNeck View Post
Unless he has a Dana 60.
You're right. Then,it would be 4.11. But,that's 1/100th lower .
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Old 08-24-2013, 09:21 AM   #10
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Re: K20 Gear Ratio Question

I'm a little late here but good chart Tim, thanks for posting.

Quote:
Originally Posted by SS Tim View Post
4.10
According to your chart, looks like we cant say becuase he didn't tell us which engine. If the truck had the 350 would be 4.10, otherwise it would be 4.57 with the 307.

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A Dana 60 stock on a '72 K20 ?????
GMC K20's got the D60. Nice thing about them is the drums are outside the hubs! And 3.54 tolerance.

Quote:
Originally Posted by special-K View Post
You're right. Then,it would be 4.11. But,that's 1/100th lower .
Sometimes I think about swapping in a D60 since they accept 3.54's. That could be a good combo with right tire size.
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