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Thread: GM Rear Ends
          
   
   

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  1. #1
    Triker is offline CHR Member Visit my Photo Gallery
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    Question GM Rear Ends

     




    Whic GM cars and years had 2.73 rear ends? (GU2)


  2. #2
    glennsexton's Avatar
    glennsexton is offline CHR Member/Contributor Visit my Photo Gallery
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    Well that's one of these "Have you stopped beating your wife?" questions. No easy answer. I know for sure every F bodied Third Generation GM car (1982–1992) had the GU2 as an option - depending on the engine transmission combination. It would be safe to say that there are a gazillion of these rear ends in bone yards across America.

    From the rear end "bible of information that I may someday use":

    Rear Axle Code example: GU2 O 030 1 EO
    GU2 = Ratio - 2.73:1
    O = Plant - Oldsmobile
    030 = Day of year – January 30 (uses Julian Date, i.e., 1 = January 1st - 365 = December 31 [except Leap Year December 31st is 366])
    1 = Shift – Day Shift
    O = Positraction Code – Oldsmobile Positraction

    Assembly Plant Codes:
    B = Buick
    C = Buffalo NY
    D = Cadillac
    G = Detroit Gear & Axle (OEM to General Motors)
    K = General Motors of Canada -
    W = Warren, MI
    O = Oldsmobile
    P = Pontiac
    M –= Pontiac of Canada

    Shift:
    D or 1 = Day shift
    N or 2 = Night shift

    Positraction Code:
    Blank = Non Positraction
    D = Dana Positraction Differential
    E = Eaton Positraction Differential
    G = Chevrolet G&A Positraction Carrier
    O = Oldsmobile Positraction Carrier
    W = Warren/Warner Motive

    Positraction Casting Numbers for 8.5" "Corporate"
    Casting # Series - Gearing
    410408N 3 - 2.73:1 and lower (larger numerically)
    410409N 2 - 2.56:1 and higher (smaller numerically)

    Rear Housing Casting Date
    Example: E143
    E = Month - May
    10 = Day – 10th
    3 = Last digit of year - 1993

    Month: A = January, B = February and so forth incrementally through L = December

    As to actual ratio codes - there's too many to list - Google them.

    No guarantees here as I've seen some exceptions.Always need to take take the cover off and count teeth to be sure.

    Best,
    Glenn
    "Where the people fear the government you have tyranny. Where the government fears the people you have liberty." John Basil Barnhil

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