1978 Estate Wagon Rear End Ratio

Discussion in 'Got gears?' started by dmfconsult, Nov 7, 2017.

  1. dmfconsult

    dmfconsult Devil in a Blue Dress

    Hoping someone might have this information handy, as I'm trying to identify the rear end in my 78 Estate Wagon. I suspect it's the standard 2.73 but want to be sure... The stampings on the axle are "2YJ P185D". I can decode that as a Pontiac sourced rear end built during dayshift on July 4, but the 2YJ is what is stumping me.

    All I can find online is a reference to RPO codes (which I will get next time I'm at the car's winter storage). Thanks in advance!
     
  2. dmfconsult

    dmfconsult Devil in a Blue Dress

    Thanks for looking guys... I've been able to confirm that 2YJ decodes to a 3.08 non-posi rear.
     
  3. Mark Demko

    Mark Demko Well-Known Member

    3.08 is a decent gear, your wagon have the Buick 350?
    I'm gonna guess the sedans had a 2.41 gear.
     
  4. monzaz

    monzaz Jim

    yah but what size rear is under that wagon...Most likely the 8.75 Pontiac rear. Send a pic or 2. Jim
     
  5. Mark Demko

    Mark Demko Well-Known Member

    Its probably an 8.5 being its a 1978 wagon, second year for the downsized full size cars.
     
  6. monzaz

    monzaz Jim

    78-85 ALL WAGONS GOT THE UPGRADE 8.75 REARS. if it is a 8.5 probably someone swapped it out.
     
    Mark Demko likes this.

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