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  1. #1
    Jr. Apprentice bobby's Avatar
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    Default want to change 6 to 8 lug, can u help!!!!!!

    Im New To This Forums And This Is My First Post, I Just Purchased A 91 1/2 Ton Silverado Extended Cab 4x4.it Has The Standard Small Block And Th700r4/4l60e .the Transmission Is Leaking Through The Output Shaft Seal And Leaking Where Transfer Case Mates To It.has Anyone Experiensed This?ive Searched And Apparently The Transmission Needs To Be Opened To Replace The Seal.a Friend Sold Me A 91 3/4 Ton 4x4 ,im Going To Pull The Tranny And Install It In Mine ,my Question Is , Can I Replace My 6 Lug Axles To 8 From The 3/4 Ton . What All Is Involved ?i Have Some Idea But Would Like Some Feedback.the Reason Im Asking Is Because The 3/4 Ton Has A Real Nice Set Of Wheels ,i Wana Know If Its Worth It Other Wise ,ill Have To Sell Them.

  2. #2

    Default

    provided that the rear axles are the same (ie 12 bolt rearend),I would think that if you opened up the differentials on both and pulled the axles, you should be able to stick them in the new diff housing. It's pretty easy with a 91 suburban rearend with the 8.5" 10 bolt rearend. Hope this helps...
    Christopher

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 277K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half



    There are 10 kinds of people, those who understand binary, and those who dont...

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  3. #3
    Jr. Apprentice bobby's Avatar
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    Default

    the 3/4 truck is a 14 bolt, 10.5 ring gear. Im hoping the axle shafts splines are the same.It looks like i will probably have to swap rear ends. as far as the front spindles ;is it a matter of just swaping the rotors? I will know more but first I have to get the truck home and compare them .

  4. #4
    Jr. Apprentice CaJuN625's Avatar
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    Default 3/4 ton

    I THINK the 3/4 ton is a 14-bolt 9.5 ring, not a 10.5. The 10.5 is a 1-ton axle. My 2500HD is a 14-bolt 10.5 ... but it's the HD version and it's newer.

    I don't believe the older 3/4 ton trucks used 1-ton running gear.

    Also, the 14/10.5 is a full floater. The 14/9.5 wouldn't be, if I recall correctly.

    Just get a new set of rims.
    CJ
    Pleasant View, UT

    1998 Tahoe LT 4dr 4wd
    2004 GMC 2500HD CC / SB

  5. #5
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    TrailLeadr's Avatar
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    Default

    14 bolt is a 10.5inch gear.
    Patrick
    Rhode Island


  6. #6
    Jr. Apprentice bobby's Avatar
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    Default

    OK. this is an update ,I decided that its not worth swaping axles at all.so thats that. My transmission(700r4/4l60e) in my 91 1500 silverado 1/2 ton 4x4 only shifts from first to second and then the engine just revs freely, checked fluid level and its full, its also leaking where the transfer case meets the tranny, is this a common problem?Is it an easy fix ?I also found out that the transmission from the 91 gmc 2500 3/4 ton 4x4 is bigger its a 4l80e and the wiring is diferent. Is the transmission swap worth it or should I just drop that also and just fix my original?
    Last edited by bobby; 08-03-2007 at 03:42 PM.

  7. #7

    Default

    Are the 91 model Suburbans equipped with a 4L60E? I thought they had straight 4L60 transmission (the "E" standing for electronic). I've never really gotten under my truck to look, but I though my 91 Sub 1/2 ton was a non-electronic...but I have been known to be wrong.

  8. #8
    Jr. Apprentice bobby's Avatar
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    Default

    also want to mention both trucks use the same transfer case. I want to make correction , my transmission is 700r4/4L60 .(no E).
    Last edited by bobby; 08-04-2007 at 09:55 PM.

  9. #9
    Jr. Apprentice CaJuN625's Avatar
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    Default There are (2) 14-bolt axles

    Quote Originally Posted by TrailLeadr View Post
    14 bolt is a 10.5inch gear.
    There are definitely (2) 14-bolt rear ends for GM:

    "The 14 bolt, 9.5" Semi-Floaters were installed on the 1990-1993 454SS trucks and the F44 equipped Z71 1/2 ton trucks and diesel suburbans as well as 3/4 ton trucks.

    The 14-bolt, 10.5 is a full floating 1-ton axle." Hog from the Duramaximizer website.

    Visually, the 9.5" has a more ROUND cover, whereas the 10.5" has the back-to-back trapeziodal looking cover.

    Also, you can pop the axles out of a 10.5" full floater without taking the rear-end cover off - no "c' clips. I don't think you can do that with the semi-floater.

    Best to note: the 9.5" 14-bolt is still a MAJOR upgrade from the 8.5" 10-bolt. It's just not apt to take the abuse that a 14/10.5 will take, simply in part due to the added MASS of the 10.5" gear set.

    Something else to keep in mind: spline count. There're 28, 30, 31 and 35 spline axles ... and they're not interchangeable, obviously.

    Respectfully ...

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