GM B-Body Forum, 77-79 Caprice/Impala Forum

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GM B-Body Forum, 77-79 Caprice/Impala Forum

A forum for all the owners and enthusiasts of General Motors B-Bodies from 1965-1996, but dedicated to the owners of 1977-1979 Impalas and Caprices. Join up now!


    REAR AXLE INTERCHANGE

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    BENZ85LIMITED
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    REAR AXLE INTERCHANGE

    Post  BENZ85LIMITED on Thu Nov 13, 2014 12:59 am

    HI, NEW TO THIS FORUM AND TO B BODIES, MY QUESTION IS WILL A 1973-1977 GM A BODY 8.5 REAR END BOLT INTO MY NEWLY AQUIRED 1985 LeSABRE COUPE? I WANT TO TURN UP THE WICK UNDERHOOD AND THE 7.5 CURRENTLY UNDERCAR WONT LAST LONG.. BEEN DOWN THIS ROAD BEFORE WITH MY G BODIES. I KNOW IF I SWITCH TO THE 8.5 I WILL NEED THE DONOR CARS DRIVESHAFT.

    THANKS FOR YOUR HELP
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    Sweet Seventy9
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    Location : Upstate NY

    Re: REAR AXLE INTERCHANGE

    Post  Sweet Seventy9 on Thu Nov 13, 2014 2:11 pm

    Welcome to the Forum!

    If you want a direct bolt-in, no, it won't work.  You'll need one from a 77-96 B-body.

    Here's what to look for:

    Axle Ratio RPO Code Ring/Pinion Teeth Application
    2.56 GM8 41/16 Std. Roadmaster LT1
    2.73 GU2 41/15 Std. Caprice L99 (exc. 9C1)
    2.93 GW9/GU3 41/14 Std. Caprice LT1 (exc. 9C1), Opt. Roadmaster LT1
    3.08 GU4 40/13 Std. Caprice 9C1/LT1 (Police), Std. Impala SS
    3.23 GU5 42/13 Opt. Caprice L99, Std. Caprice 9C1/L99 (Police)
    3.42 GU6 41/12 Std. 91-93 Caprice 9C1/L05, Std. 94+ Fleetwood w/V4P
    3.73 GT4 41/11 Std. 91-92 Fleetwood Brougham w/V4P

    *V4P = 7,000 lb. trailer towing package... look for a hitch.



    I think your Caps Lock button is stuck...... Smile


    _________________
    1977 Impala Landau x1
    1977 Caprice Coupe x3, Sedan x3
    1978 Impala Landau x1, Sedan x2, Station Wagon x1
    1978 Caprice Landau x1, Caprice Coupe x2
    1979 Impala Coupe x2
    1979 Caprice Coupe x7, Landau x4, Estate Wagon x1
    1981 Impala Coupe x1
    1983 Impala Sedan x1
    1983 Caprice Sedan x1
    1984 Caprice Landau x1, Sedan x1
    1985 Caprice Coupe x1, Landau x3, Sedan x4
    1986 Caprice Coupe x1, Landau x1
    1987 Caprice Landau x1, Sedan x4
    1989 Caprice Sedan 9C1 x4
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    GM B-Body Forum
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    Re: REAR AXLE INTERCHANGE

    Post  GM B-Body Forum on Thu Nov 13, 2014 7:11 pm

    Hes just mad at us already lol just kidding, anyway welcome aboard, glad you found us!
    And if your out searching for a rear end in a junk yard, those RPO codes Sweet posted are located on the trunk lid


    _________________
    1979 Caprice Sport Coupe, 400hp Vortec 350, Th350, GM 8.5 w/disc brakes, 3.90 gears Detroit Truetrac, 2.5" stainless duals w/ x-pipe, Dynomax race bullets.
    1984 Caprice Sedan, 305 motor, 700r4
    1978 Caprice Sedan, 305 motor, th350
    1993 L99 Caprice, 4.3 v8, 4l60 trans
    1972 Ford F-100, 302 windsor, c4 trans
    2001 BMW E46 330i, 3.0L
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    BENZ85LIMITED
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    REAR AXLE INTERCHANGE

    Post  BENZ85LIMITED on Thu Nov 13, 2014 11:36 pm

    Thanks for the warm welcome and sorry for all the caps....
    I remember reading in a magazine some time ago that the 1973 to 1977 GM A Body rear was a bolt in deal, do you know what obstacles I may encounter going this route? Now again I'm not at all that familiar with the B Body, but is one of the issues the wheel bolt pattern? If I remember the A body coupe and sedan used the 5x4.75 bolt circle whereas the A Body wagons and B Body used the 5x5, when they switched to the 7.5 rear I think the B Body went to the 5x4.75 pattern.
    I can get a very rough but complete 94 9C1 for cheap that would probably be the way to go
    Thanks
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    Re: REAR AXLE INTERCHANGE

    Post  GM B-Body Forum on Fri Nov 14, 2014 11:00 am

    Nope they are not a bolt in, the mounts for the shocks and springs have to be relocated which means cutting and welding.
    As far as the bolt pattern goes, to my knowledge only wagons, 9c1's, and the impala ss's only got the 5x5 bolt pattern, all the rest had 5x4.75. But i also heard or read somewhere that the models that had the HD 11'' drums also had the 5x5 pattern.

    I just swapped in a rear end from a 96 ss in my 79, check it out if you havent yet
    https://www.gmbbodyforum.com/t153-gm-85-10-bolt-swap-from-a-96-impala-ss


    _________________
    1979 Caprice Sport Coupe, 400hp Vortec 350, Th350, GM 8.5 w/disc brakes, 3.90 gears Detroit Truetrac, 2.5" stainless duals w/ x-pipe, Dynomax race bullets.
    1984 Caprice Sedan, 305 motor, 700r4
    1978 Caprice Sedan, 305 motor, th350
    1993 L99 Caprice, 4.3 v8, 4l60 trans
    1972 Ford F-100, 302 windsor, c4 trans
    2001 BMW E46 330i, 3.0L
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    BENZ85LIMITED
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    REAR AXLE INTERCHANGE

    Post  BENZ85LIMITED on Sun Nov 16, 2014 8:24 pm

    Thanks for your help, I almost purchased a rear out of a 1976 Cutlass thinking it would fit.. That would have been a real bummer when I tried to install it in the 85 LeSabre...
    I bought that 94 9C1 Caprice for real cheap, its complete!
    Again thank you for your knowledge and I just might pick your expertise one or twice again..


    _________________
    ERIC
    1978 69K C-10 400 4SPD 12 BOLT POSI 3.08
    1979 76K TRANS AM 355SBC EFI 5SPD 8.5 POSI 4.56
    1985 62K BUICK LeSABRE LIMITED COUPE SOON TO BE 9C1 EQUIPPED
    1986 104K MONTE CARLO SC 406SBC THM350 8.5 POSI 4.30
    1987 72K MONTE CARLO SS 406SBC EFI THM2004R 8.5 POSI 3.90
    1987 38K GRAND NATIONAL GARAGE QUEEN ALL STOCK
    1997 231K SATURN SL2 1.9 DOHC 5SPD 42MPG
    2001 190K CHRYSLER SEBRING LXi 2.7 AUTO
    2001 172K ELDORADO ETC NORTHSTAR EQUIPPED
    2003 108K RAM 1500 QC HEMI
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    Sweet Seventy9
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    Re: REAR AXLE INTERCHANGE

    Post  Sweet Seventy9 on Sun Nov 16, 2014 8:32 pm

    I'm glad we were able to help.

    Let's see some pics of a posi burn-out!!  LOL!!  Laughing


    _________________
    1977 Impala Landau x1
    1977 Caprice Coupe x3, Sedan x3
    1978 Impala Landau x1, Sedan x2, Station Wagon x1
    1978 Caprice Landau x1, Caprice Coupe x2
    1979 Impala Coupe x2
    1979 Caprice Coupe x7, Landau x4, Estate Wagon x1
    1981 Impala Coupe x1
    1983 Impala Sedan x1
    1983 Caprice Sedan x1
    1984 Caprice Landau x1, Sedan x1
    1985 Caprice Coupe x1, Landau x3, Sedan x4
    1986 Caprice Coupe x1, Landau x1
    1987 Caprice Landau x1, Sedan x4
    1989 Caprice Sedan 9C1 x4

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