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Old 07-06-2015, 08:28 PM   #1
scimfish
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Join Date: Jun 2015
Location: Berea, KY
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Introduction

Hi all, I have undertaken the task of restoring my grandfather's '71 C20. I am not a gearhead, nor do I have a lot of knowledge about Chevy trucks. Therefore, I will surely ask some bone-headed questions. Please bear with me, I am trying to learn! Now about the truck...it is a '71 C20 with a 250 straight six, 4 speed with granny. I have it almost stripped to the frame, getting it ready to be blasted and painted. But I have a problem; I want to change the rear end to a 3.07 so that I can turn this into a daily driver. I have run into trouble finding a rear end with this gear ratio in my area. I found one recently but it is a six lug. I have a five lug front end to put under it. Question is, if I buy aftermarket C10 ring and pinion will it fit the original 10 bolt stump and axles? If so I can just use the original 8 lug front and rear. Suggestions would be appreciated...
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Old 07-06-2015, 08:48 PM   #2
9teen69
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Re: Introduction

Welcome! It's cool you're fixing up your grandfathers truck. I'll let someone more experience with 3/4 ton answer. I would imagine you can just change the ring and pinion. Enjoy!
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Old 07-07-2015, 11:46 AM   #3
scimfish
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Re: Introduction

Okay, so after reading my initial post, I figured I had better clarify my objective. I want to squeeze as many mpgs out of this brick as possible, and all the research I have done has told me that swapping the rear end gear ratios would be the place to start. I will only be driving a two lane highway, 55-60 mph.

I want to either:
-Get a whole different rear end with a lower gear ratio (3.07??)
-Get a ring and pinion set and have it installed in the stump

Now, the rear end I currently have on it is an 8 lug, 10 bolt Dana 60(going to confirm with stampings today). It has two metal tags affixed to the housing with stamped numbers on it. From memory, it seems that one said 41011 and the other mentioned oil weight. Sorry for not being sure of this at the moment, can't get to truck right now. I will post again later, just wanted to get more info out there. Thanks in advance
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Old 07-07-2015, 12:14 PM   #4
Joesjunk
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Re: Introduction

Welcome, and congrats on restoring your grandfathers truck. As far as rear ends go, if it's a Dana 60 you have a few better options as far as changing gear ratios. If it's got he Eaton rear axle 4:10 is the best they offered for that. If you want 3:07 gears you will have to change it all over to a half ton rear axle.

Post some pics of the truck. And post a pic of the option sticker on the inside of the glove box door.
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71 3/4t Cheyenne 402 70k original paint
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72 3/4t 4x4 Custom deluxe 91k original paint
72 Cheyenne/30 Dually
69 Camaro SS396 4-speed
13 GMC 2500HD Duramax I bought new
05 Jeep Wrangler "Willys Edition" 12k miles (I bought new)
85 3/4 ton 4x4 Scottsdale 33k miles original paint
86 1 ton 4x4 SRW Silverado 454 restored
80 1 ton 4x4 SRW Silverado 9,434 original miles!! original paint
95 GMC 1 ton dually 4x4 my dad bought new
95 GMC 3/4 ton 4x4, regular cab 454, 31k original miles
2002 2500HD 4x4 regular cab 6.0L 67k miles
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Old 07-07-2015, 05:58 PM   #5
scimfish
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Re: Introduction

Okay, so here is what I have...
Casting # C30255, 60
Axle housing # 3119A1. 317(unreadable)...
Glove box code G50/ heavy rear spring, G70/rear suspension leaf....
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Old 07-08-2015, 12:11 AM   #6
Joesjunk
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Re: Introduction

I'm believe you would have the Dana 60. I know they had a 3:54 ratio in these trucks, but only with a big block. You might be able to find one and swap it. Or check online to see what gear options are available for a Dana 60. With a 6cyl, your truck would have a 4:56 gear, unless 4:10 was ordered.
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72 3/4t Custom Deluxe 402/auto 66k Original paint
71 3/4t 4x4 Custom Deluxe 10k original miles Original paint
71 3/4t Cheyenne 402 70k original paint
72 3/4t 4x4 Custom deluxe
72 3/4t 4x4 Custom deluxe 91k original paint
72 Cheyenne/30 Dually
69 Camaro SS396 4-speed
13 GMC 2500HD Duramax I bought new
05 Jeep Wrangler "Willys Edition" 12k miles (I bought new)
85 3/4 ton 4x4 Scottsdale 33k miles original paint
86 1 ton 4x4 SRW Silverado 454 restored
80 1 ton 4x4 SRW Silverado 9,434 original miles!! original paint
95 GMC 1 ton dually 4x4 my dad bought new
95 GMC 3/4 ton 4x4, regular cab 454, 31k original miles
2002 2500HD 4x4 regular cab 6.0L 67k miles
2002 2500HD 4x4 regular cab 8.1L 28k miles
2003 GMC 2500HD 4x4 regular cab Diesel 93k miles

67-72 Parts for sale
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