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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 end swap

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    GEOLANG1
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    Rear end swap

    Post  GEOLANG1 on Thu Apr 18, 2013 9:32 pm

    What rear ends with a limited slip diff can be bolted into a 79 Caprice with out any modifications. A direct replacement. Looking to bolt one into mine.
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    Re: Rear end swap

    Post  GM B-Body Forum on Fri Apr 19, 2013 7:13 pm

    all the rear ends from 77-96 will bolt right up and that includes the 94-96 impala ss


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    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

    GEOLANG1
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    Re: Rear end swap

    Post  GEOLANG1 on Fri Apr 19, 2013 9:02 pm

    That's good to know. Thank you

    bigbluebox
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    Re: Rear end swap

    Post  bigbluebox on Sun Jun 23, 2013 11:26 pm

    hi, im new to the site. i would like to know what rear ends will fit that have a 8.5" ring gear. thanks
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    Re: Rear end swap

    Post  GM B-Body Forum on Mon Jun 24, 2013 3:02 pm

    Welcome and thanks for joining! I myself am not an expert on rear ends. I have heard some buicks, cadillacs, and some gm trucks will bolt in, but i dont believe the buicks and caddys had 8.5 except maybe for the turbo buicks, not sure! If your planning on putting down some serious power like I plan on too, then id go for a 12 bolt. The spring mounts will have to be moved and rewelded, i also believe that this will be your only problem, is the suspension mounts. I wont know til I get there! Ill see if my buddy knows anything else.


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    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

    bigbluebox
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    Re: Rear end swap

    Post  bigbluebox on Mon Jun 24, 2013 11:31 pm

    yea. honestly im kinda planning on putting a 5.3L from a 99-08 chevy. a 12 bolt is a good suggestion, i was just lookin for a direct bolt in for easy install. do you have any idea what gear ratio we have? i also have a 79. its a 4 door 350 with a quadrajet and a th350 trans. hope the forum takes off, glad i found it
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    Re: Rear end swap

    Post  GM B-Body Forum on Tue Jun 25, 2013 6:08 pm

    You most likely have a 2.41 gear which sucks around town, I know. Im assuming you dont have the build sheet it would say on there. You can also get under the car and see if there is a tag on the differential that says "use limited slip diff fluid only" if you got that tag then you have a 3.08 gear posi which was optional and I wish mine came with it. There were only 3 ratios offered, the 2.41, 2.73(wagons only) and the 3.08. And thanks bud I hope it does too. Oh yea, what kind of 5.3 are you planning on putting in?


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    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

    bigbluebox
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    Re: Rear end swap

    Post  bigbluebox on Tue Jun 25, 2013 10:52 pm

    Im sure I have it somewhere because im ony the second owner lol. but on the pre delivery inspection sheet the axle number is 2gf c120 2 but the original owner had a posi put in at the dealership. ill probably get a used 5.3 from a chevy truck and swap out the cam for a ls6 cam and ls6 valve springs. Ill probably get the edlebrock performer rpm with the msd 6ls box
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    Re: Rear end swap

    Post  GM B-Body Forum on Tue Jun 25, 2013 11:29 pm

    Thatll be a decent motor and setup, should get you 400hp all day. Same on my build sheet, 2gf, i believe thats the 7.5 carrier, then theyd just drop in whatever gear ratio. You know i have heard some folks running 9s using a highly modded 10 bolt.


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    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

    bigbluebox
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    Re: Rear end swap

    Post  bigbluebox on Wed Jun 26, 2013 9:45 pm

    Yeah, its an incredibly strong engine design too. It should even get better gas milage. Do u think I could find a 3:42 gear or even a 3:73 for now? And keep my posi? I was a mechanic for a while but im new to modifying old cars, I just fixed modern ones lol.
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    Re: Rear end swap

    Post  GM B-Body Forum on Thu Jun 27, 2013 8:21 am

    I know you can get a 3.08 but i do believe anything bigger, and youll have to get a 10 bolt 8.5, simply because no one cares about the smaller 10 bolts and no one makes anything for them really. Now if this is stricktly gonna be strip car then id go for a 3.55 or higher, but if your driving this on the street 99% of the time, id go no bigger than a 3.08 with a th350 or 400, unless you get an overdrive tranny. Gas mileage will begin to suck, youll be turnin 3500 rpm at about 70mph, depending on tire size. I know Moser has differentials and gears for the 8.5, but anything to do with rearends is expensive.


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    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

    bigbluebox
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    Re: Rear end swap

    Post  bigbluebox on Thu Jun 27, 2013 8:11 pm

    actually after posting that i was on summit's web site and they do make bigger than a 3.08 but i would not trust anything bigger than a 3.08 with anything other than a bone stock engine because i would guess the gears would be very thin. i don't drive the ole girl very often and when i do, its not usually on the interstate. im just thinking a 3.42 would make it a little more fun to drive till i do the swap. it wont be a strip car but it wont see much interstate time either. after the swap it will probably he a new rear end. i live in west virginia and we have alot of fun curvy roads so i want it set up for that.
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    Re: Rear end swap

    Post  GM B-Body Forum on Thu Jun 27, 2013 8:25 pm

    I live in North Carolina and we got those same curvy twisty roads, they are fun and i cant wait until i overhaul the suspension and see how much better it handles. Id put a 3.73 in if i were you, since it wont see the interstate, and it will literally be a boatload of fun around town!


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    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

    bigbluebox
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    Re: Rear end swap

    Post  bigbluebox on Thu Jun 27, 2013 9:19 pm

    good point. i cant even spin the tires in mine even with the stock wheels and tires since its a posi and such a high gear. im planning on doin some handling upgrades too, its crazy how much better it handles with just my iroc z wheels on it. im on a tight budget so im going to get front coils and both swaybars from a 96 impala ss with new poly end links. the budget is also why im going with a used 5.3 swap instead of a 383 crate motor lol.
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    Re: Rear end swap

    Post  GM B-Body Forum on Thu Jun 27, 2013 9:59 pm

    I know, i got a 2.41 and its hard to do a burnout if its in the mood lol, i can squeal the tires if i nail it from a dead stop or turn right and floor it, but its funny, when its raining, cant get traction for nothing and thats even with new tires, wheels will just spin, and i know all about that "budget" im on one of those too lol


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    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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    Re: Rear end swap

    Post  bigbluebox on Thu Jun 27, 2013 10:59 pm

    lol yea in the rain, not only do i have a hard time with traction, but being posi trac i wont stay straight. the last time i drove it in the rain, i had the iroc's on it drivin up a hill at 45mph and couldnt keep it in my lane. i had slowed down to the point i thought i was gonna have to back down the hill. when i made it to the top and finally got traction i was going 10mph lol.
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    HeavyChevy77
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    Re: Rear end swap

    Post  HeavyChevy77 on Wed Jul 03, 2013 8:08 pm

    For the axle swap you need the drive shaft of the impala as cuz its short that the driveshaft of the 7.5" 10 bolt ...my question is will 77 caprice trailing arms bolt on right with a 91-96 impala as
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    Re: Rear end swap

    Post  GM B-Body Forum on Wed Jul 03, 2013 11:16 pm

    Yes they should, but if your putting a 94-96 impala ss rear in, take the upper and lower trailing arms too, because then youll be able to use a sway bar.


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    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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    Re: Rear end swap

    Post  HeavyChevy77 on Wed Jul 03, 2013 11:35 pm

    Thanks man it cause the as axle is a lil wider ... I've been hunting for a solid we axle
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    Re: Rear end swap

    Post  GM B-Body Forum on Thu Jul 04, 2013 10:11 am

    yup, I believe its 5/8 of an inch wider, everything should bolt up with no problems.


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    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

    Either35
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    Re: Rear end swap

    Post  Either35 on Mon Jul 06, 2015 11:34 pm

    Hey guys new to the forum.... I have a ?.. I have a 1978 caprice that I'm looking to swap over to coil overs... Any ideas of what rearends are comparable any and all info is appreciated
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    Fierro51
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    Re: Rear end swap

    Post  Fierro51 on Thu Jan 28, 2016 1:06 pm

    whats the factory rear end width on these 77-79 impalas


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    Re: Rear end swap

    Post  GM B-Body Forum on Thu Jan 28, 2016 3:14 pm

    Fierro51 wrote: whats the factory rear end width on these 77-79 impalas
    Well they came with at least 3 different rear ends, with different brake options, so it would be hard to answer that.


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    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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    Re: Rear end swap

    Post  Fierro51 on Thu Jan 28, 2016 8:59 pm

    GM B-Body Forum wrote:
    Fierro51 wrote: whats the factory rear end width on these 77-79 impalas
    Well they came with at least 3 different rear ends, with different brake options, so it would be hard to answer that.
    I see. what widths came with which brake options? or were they completely intermixed ?


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