Rear end ratio
Thread Starter
8th Gear
Joined: Sep 2015
Posts: 8
Likes: 1
Rear end ratio
My 79 vette has a rearend stamp of AW A 06 0 E 1
Can someone tell me for sure is that a 3:08 Ratio and what it all means I looked some up and in my 79 it maybe isn't the original rearend ????
Thanks
Can someone tell me for sure is that a 3:08 Ratio and what it all means I looked some up and in my 79 it maybe isn't the original rearend ????
Thanks
Instructor
Joined: Sep 2022
Posts: 124
Likes: 29
From: Poconos
The only sure way to know the ratio is to mark the tire and driveshaft. Rotate the tire 1 revolution and count how many times the driveshaft turns. I have no knowledge of the originality part.
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,051
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From: US-PNW
I am having a tough time finding my date code translation guide, but I think it's January 6th, 1970, Eaton, shift 1. But that is kinda troublesome because 1970 Corvettes used CAW while '69 and '71 used just AW. That's also complicated by the extended 1969 model year into December of '70...
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
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Cruise-In VIII Veteran
Just because the case is stamped with a factory stamp from 50 years ago, and then not even in the original car,
Well, basically means nothing.
Could be anything in that case now. Mark the drive shaft and count.
Who would put in a 3:08 on purpose?
Well, basically means nothing.
Could be anything in that case now. Mark the drive shaft and count.
Who would put in a 3:08 on purpose?
Instructor
Joined: Sep 2022
Posts: 124
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From: Poconos
Racer
Joined: May 2025
Posts: 331
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From: Georgia
True,
I removed my 3:08 to make room for a 3:73
Melting Slicks
Joined: Oct 2003
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From: Chapel Hill NC
2025 c3 ('68-'73) of the Year Finalist - Unmodified
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If you don't want to jack up the car and count revolutions I believe here are formulas on line that can determine the rear diff ratio based on tire size, vehicle speed, and RPM.
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Tech Contributor
Joined: Aug 1999
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From: Connecticut, USA
The last AW code was used in 1975 for the 3.08 gearing, as a matter of fact, all uses of AW were for 3.08.
I am having a tough time finding my date code translation guide, but I think it's January 6th, 1970, Eaton, shift 1. But that is kinda troublesome because 1970 Corvettes used CAW while '69 and '71 used just AW. That's also complicated by the extended 1969 model year into December of '70...
I am having a tough time finding my date code translation guide, but I think it's January 6th, 1970, Eaton, shift 1. But that is kinda troublesome because 1970 Corvettes used CAW while '69 and '71 used just AW. That's also complicated by the extended 1969 model year into December of '70...
Now, if it is a 1975 diff and original, just bolted into the car, there are some issues within it that should be checked. Maybe they were already addressed, maybe not. If the diff is not leaking, whining, or has excessive axle endplay I would drive the car. If it has any or all of those, I would consider checking it more closely and that means removal.
There is casting date on the lower left side, look to see what it is. Chances are it is not the original diff. That doesn't mean it is bad, I use a lot of 72-79 housing for foundations to build much stronger diff's from.