Chevy rear end gear ratio?

Discussion in 'Shop Talk' started by Ed Norman, Nov 8, 2005.

  1. Ed Norman

    Ed Norman Well-Known Member

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    The rear end on my 92 Chevy half ton with 4.3 litre 6 shelled out this weekend. I bought it new and it only has a quarter million miles. I have the original window sticker and all it says is "locking differential". It doesn't give any gear choices in the owner's manual either. I know it had some tall gears, and I have to go back with the same ratio so it matches the front differential. I can't just jack it up and turn it to determine ratio, because it is locked solid. We had to skid it off the trailer when we got it home.

    Any ideas?
     
  2. Darren

    Darren Still an :censored:

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    Any GM dealer should be able to use the VIN to tell you the ratio. Since the front axle still works, you can rotate rotate a front tire and check how many times the front drive shaft turns. If you're running a 4.10 or 4.11, that means rotatating the front wheel one turn will see the drive shaft rotate a bit more that four times.

    Usually the front and rear gears aren't exactly the same but will be something like a 4.10/4.11 matchup. Again the parts counter guy at a GM dealer should be able to tell you.
     

  3. DrippingSprings

    DrippingSprings In Remembrance

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    look for a small metal tag held on by one of the bolts on the rear end. it has the gear ratio.
     
  4. Beeman

    Beeman Well-Known Member

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    No metal tags on Chevy, only Ford. In the glove box there is a sticker with all of the option codes. One of those codes refers to the differential ratio and if it's a locking differential. If I remember correctly it would start with a G like G80. I have the book to decode this but it will take time for me to get back to you. The dealer should be able to tell from the VIN at the parts department. they can enter your VIN and all of the correct parts are highlighted. There is usually a code stamped in the top of the axle tube, I believe it's the left tube. You will need a wire bruch and a mirror to read it.
     
  5. BigBoy

    BigBoy No attitude here...

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    All GM vehicles have an RPO (regular production option) tag somewhere. I think on your truck it will be in the glovebox. A white label a bit smaller than an envelope with 3 digit number and letter codes on it like RB1, GC4, etc. The codes starting with G usualy are for the rear end gears. You can then decipher the code here... RPO Codes