3.75 vs 4.25 Diff. Front yoke interchangeability
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Intermediate
Joined: Nov 2014
Posts: 38
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3.75 vs 4.25 Diff. Front yoke interchangeability
I recently purchased a differential out of a 66 corvette that has 4.56 gears to replace my current stock 3.08 differential in my 75 corvette. I was told 63-79 use the same differential but it appears the front differential yoke on one appears to be a 3.75 yoke and the other is a 4.25. Does anyone know if these are interchangeable? If the spline count is the same on both pinion splines wouldn't it be possible to just pull the old one off the 3.08 diff. And put it on the 4.56 since they have a different ujoint type. If they are not what option do I have without having to replace the driveshaft for the different strap/bolt type ujoints do they make a combination ujoint that would work? Your help is appreciated
Thanks
Matt
Thanks
Matt
Last edited by Sponzie; Jul 6, 2015 at 06:23 PM.
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
The spline count is the same 65-79. 63-64 are different.
Your 75 uses 1330 series driveshaft u-joints.
The 66 uses 1310 series.
If I remember correctly the conversion u-joint is Spicer 5-134X.
Mike
Your 75 uses 1330 series driveshaft u-joints.
The 66 uses 1310 series.
If I remember correctly the conversion u-joint is Spicer 5-134X.
Mike
Le Mans Master
Joined: Dec 2003
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From: Fremont CA
WARNING! You have to get the pre-load correct on the pinion bearings when swapping the yokes, it isn't an easy task to accomplish. If you don't get this figure right you will destroy your differential.......
Race Director
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From: Corsicana, Tx
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I agree,,,,unless you're good at it....I'd just swap the ujoint.
JIM
JIM
