rear end question

Discussion in 'Transmission & Driveline Topics' started by younda, Mar 14, 2018.

  1. younda

    younda Veteran Member

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    I wanted to find a 3:42 posi for my 74 Z28 and found one from a 1980 Z28 parts car. What's the difference besides the stamping on 74 vs. 80? The reason for asking is I found a correct CM code 74 but the price is very high and the 1980 is very reasonable.
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    1980 should have a PY coded rear for 3.42 posi. Other than the code, the rear end should be basically the same as the 1974 rear ends.
     
  3. slayer021175666

    slayer021175666 Veteran Member

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    Its the same. Buy it.
     
  4. 74BIBELOT

    74BIBELOT Veteran Member

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    Check the pinion yoke, could be different, but you can use the appropriate u joint.
     
  5. Green hornet

    Green hornet Veteran Member

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    If it fits your budget by it. What would be the reason for purchasing correct code one?
     
  6. big gear head

    big gear head Veteran Member

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    The pinion yoke will be different. The '74 will use a 1310 U joint and the '80 will use a 3R U joint. You will need the '80 drive shaft or you will have to use an adapter U joint in your drive shaft. Also, the mounting bracket for the rubber brake line will probably be in different location.
     
  7. NoneToPass

    NoneToPass Veteran Member

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    Yep, the 80 bracket is welded to the drivers side tube and the 74 mounts to the diff. cover. Brake lines can be swapped over from your current rear and disregard the 80 bracket.
     
  8. younda

    younda Veteran Member

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    67CFC4CE-D93D-4C4F-8D55-B424E99CE3F0.jpeg 8A08D0CB-CB70-4F34-8CD5-9E8021E7295D.jpeg Thank you for the information. I got the PY with only 50k miles for $350. Got the history of the car which was in a garage for over 25 years.
     
    Last edited: Mar 17, 2018
  9. ZEN357

    ZEN357 Veteran Member

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    Should be the same. I would buy it.
     
  10. tom3

    tom3 Veteran Member

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    If needed your local NAPA dealer can furnish the conversion U-joint if you can get the measurements or part number for them.
     

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