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Diff ratio change?

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Old Mar 10, 2014 | 10:06 PM
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Default Diff ratio change?

I found that my 76, has a 3.55 diff. Obvious change by PO. This explains the tach readings at 65 mph. I personally would prefer better mileage and lower rpms. The engine has an edelbrock intake and Holley carb as well. Would there be an issue with changing to the 3.08 diff. There is a bit of yoke play, I'd say 1/8"+ left side and 3/16" + rt side. I'll get an inside look when I drop it to change the leaking gasket. My intent is to have a reliable distance driver, 300-400 miles per day, for family visits and or over nite sight seeing trips. Thanks.

Last edited by Higgy76; Mar 11, 2014 at 07:45 PM. Reason: Clarity
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Old Mar 10, 2014 | 10:57 PM
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I got a 3.08 out of my 76 - have no issues at all with it - I'd be interested in a swap. I have no rear cover - I used it on my other diff.
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Old Mar 11, 2014 | 01:00 AM
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Had I only known....

My 74 Convertible had 3:08's. I Just,and I mean JUST got the gears changed out and rear end gone through with a rebuild kit tonight. Yup. You guessed it. I'm going with 3:73's, however it's backed with a 4L60e so the overdrive will make it highway cruise-able yet still funner than batpoo to drive. These days it seems you CAN have your cake and eat it to... Have ya considered a transmission swap? You can put a 700R4 in and still use the old school motor. Oh...then you can leave that perfectly fun gear ratio.
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Old Mar 11, 2014 | 01:53 PM
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Originally Posted by Higgy76
I found that my 76, has a 3.55 diff. Obvious change by PO. This explains the tach readings at 65 mph. I personally would prefer better mileage and lower rpms. The engine has an edelbrock intake and Holley carb upgrades as well. Would there be an issue with changing to the 3.08 diff. There is a bit of yoke play, I'd say 1/8"+ left side and 3/16" + rt side. I'll get an inside look when I drop it to change the leaking gasket. My intent is to have a reliable distance, 300-400 miles per day, driver. Thanks.
3.08 is the most common differential. There are a lot more guys wanting to go from 3.08 to 3.55 than the other way. A trade sounds like a good option.
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Old Mar 11, 2014 | 05:08 PM
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For a "300-400 miles per day" car, I wouldn't consider a Holley carb an "upgrade".

But... I'd be considering going to an overdrive transmission, that would make the car really purr.

Before that, I'd be looking at a different car to drive every day. For a *lot* of reasons...
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Old Mar 11, 2014 | 07:48 PM
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Originally Posted by Shark Racer
For a "300-400 miles per day" car, I wouldn't consider a Holley carb an "upgrade".

But... I'd be considering going to an overdrive transmission, that would make the car really purr.

Before that, I'd be looking at a different car to drive every day. For a *lot* of reasons...
Thanks for the info. I think the overdrive is a likely option.
Higgy
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