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Old 03-05-2010, 08:28 PM
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3.31 or 3.73 ?

I have a '69 El Camino with a Fairly plain 383, 700r tranny on my car. I'm getting it road ready because I need a daily driver right now. I have 2.56 rear gears on a 10 bolt. I can buy a 3.31 rear end off a '66 Chevelle pretty cheap which would allow me to get bigger tires BUT I also want some Torque too !! I'll be doing about 30 miles of Highway a day & some in town driving as well. Do I get the 3.31 or am I just better off getting the 3.73 gears now ??

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Old 03-05-2010, 08:33 PM
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The 3.31 is a nice gear for something that has to see a little highway every day and still have some hot rod pep. I'd jump on that rear if the price is real good, it's narrower than your current rear and a decent road gear which are both a plus
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Old 03-05-2010, 08:34 PM
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Since you've got an overdrive tranny I would spring for the 3.73.
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Old 03-06-2010, 09:41 AM
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The 700R4 transmission has a low 3.06 first gear, which would work well with the 3.31 gears. I'm assuming that this is a 12 bolt because of the 3.31. A '66 12 bolt is rare and getting expensive. The spring perches are going to be different from your '69, so be sure to get the clamps that hold the springs at the bottom. Thee 383 should have plenty of torque for the 3.31 with overdrive, as long as you don't have a wild cam in the engine.

A 3.73 is going to cause the 700 to shift out of first gear pretty quick and will cause the drive shaft speed to be higher at highway speeds. This might cause a very slight ballance problem with a stock drive shaft. Some people get a slight harmonic vibration when going this far with a stock drive shaft and overdrive transmission.
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Old 03-06-2010, 01:50 PM
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i like 3.73 gears, but with what you have i think the 3.31's would be fine. if it doesn't suit you, replace them when you have the money.
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Old 03-06-2010, 09:15 PM
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BigGearHead is right about the 3.31 being a 12-bolt gear, if this is a '66 Chevelle 10-bolt then it is a 3.36 gear.

Just more of that useless info off the top of my head
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Old 03-08-2010, 05:57 AM
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Yah,it's a 10 bolt. I'm gonna throw it in for now & Upgrade this summer. Thanx Fellas !!
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Old 03-08-2010, 09:33 AM
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So it's a 3.36 and not a 3.31.
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