12 bolts install question

Discussion in 'Got gears?' started by scubasteve455, Apr 29, 2018.

  1. scubasteve455

    scubasteve455 Well-Known Member

    I want to install a Pontiac judge 12 bolt in my 72 GS will it fit.?Is the drive shaft in the Buick GS gonna be to long? Or will I be OK ?
  2. monzaz

    monzaz Jim

    If you have the original 1972 10 bolt 8.5 in your 72 GS the drive shaft with the swap of a 12 bolt CHEVY rear will need to be LENGTHENED...not shortened.
    10 bolt 8.5 out of all GM A-body rears has the longest pinion shaft. almost all other a-body rears are interchangeable with only a minor u-joint swap at the most.

    J D
  3. scubasteve455

    scubasteve455 Well-Known Member

  4. scubasteve455

    scubasteve455 Well-Known Member

    Will the Neapco 3-3130 give me the length that I need ? Or do I need a drive shaft? I thought that because the 12 bolt was B. O. P. That it would be ok. Jim are you saying I need a dive shaft?
  5. scubasteve455

    scubasteve455 Well-Known Member

    Yes my car has the original 72 lwb 10 bolt 8. 5
  6. scubasteve455

    scubasteve455 Well-Known Member

    Jim could you give me the Measurement. I will get this driveshaft extended. I’m sure That number gets thrown around a lot. Or would I be better off with a new driveshaft
  7. scubasteve455

    scubasteve455 Well-Known Member

    Or I could measure from tranny seal to flat part on axle yoke.
  8. monzaz

    monzaz Jim

    You have to call your driveline shop your going to use and ask them how they want it measure...THIS IS the only safe way to get a driveshaft built.
    Besides i do not know the driveshaft length...lol. Nor would it matter if you want it done right.

    J D
  9. Bens99gtp

    Bens99gtp Well-Known Member

    As Jim said measure how the shop your using want and have a new one made. I cant see any safe way to extend a shaft.

    I use a place just outside of Columbus Ohio called custom clutch and joint. Never had a safe they built me fail never been over 300 but I always provide then the slip yoke I'm using and use it to get the measurement. Mike is super to deal with. I'm sure they will ship to where ever. 614-850-0337
  10. scubasteve455

    scubasteve455 Well-Known Member

    Ok Jim you are correct talk to a driveline guy here in Pgh. Thank you very much for your time. Thanks Ben
  11. BrianTrick

    BrianTrick Brian Trick

    One option is to use a trans yoke,with a longer barrel,but make sure it is splined to the end. It is not a cure-all/end-all solution,but it does work occasionally,depending on how much length you are trying to make up.
    I have also put an 8.5” yoke on a 12-bolt Chevy,using a different seal,and then you can retain your existing 3R u-joint.
    A combination of both could do it too.

    Attached Files:

  12. 87GN_70GS

    87GN_70GS Well-Known Member

  13. scubasteve455

    scubasteve455 Well-Known Member

    Scott Thanks!! Did not know. I will Fab One. Good info. I Appreciate

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