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91 3/4 ton 4X4 has which OD tranny?

Discussion in '1936-Present Suburban' started by mini_mull, Apr 25, 2005.

  1. mini_mull

    mini_mull 1/2 ton status

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    Would a 91 3/4 ton 4x4 burb have a 700R4 or a 4L80E? And what's the diff? Is the 4L comp controlled and a bigger pain to mess with, or are they about the same?
     
  2. mini_mull

    mini_mull 1/2 ton status

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    OK, I found a post that mentioned the Light Duty had the 700R4, but they are rare, most are HD 8600 GVWR and had the 4L80E. But I am still wondering how much more complicated the install of a 4L80E would be than a 700R4, and if you swap engines and need a custom chip, is it more complicated and expensive because of the comp controlled 4L80E?
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    A 91 may have the 4L80E. Pray that it does. They are WAY superior to 700R4's. They are computer controlled but they run off a stand alone computer from what I have heard.

    The 4L80E is alot stronger then a 700R4.
     
  4. mini_mull

    mini_mull 1/2 ton status

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    So the 4L80E comp is not connected to the ECM that runs the TBI?
     
  5. dhcomp

    dhcomp 3/4 ton status Premium Member

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    What he said, it should be a 4l80e in the 91 3/4 ton, but it has a stand alone computer.
     
  6. mini_mull

    mini_mull 1/2 ton status

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    Great, thanks guys. Sounds like the perfect tranny, esp with the separate computer.
     
  7. afroman006

    afroman006 1/2 ton status

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    I just tore apart a 91 dually with 454 and 4L80E and it only has one computer. Me thinks the engine and tranny puters work together.
     
  8. dhcomp

    dhcomp 3/4 ton status Premium Member

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    OK, well maybe its not a seperate computer...but thats always what i had heard.

    Either way though, that tranny kicks ass. Way better than the 700r4. So it doesnt' really matter how its controlled - you're lucky to be getting the one year of the old body style burb that came with that tranny.
     
  9. afroman006

    afroman006 1/2 ton status

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    Yes, I have one. Me sell it this summer though.
     
  10. azblazor

    azblazor 1/2 ton status Premium Member

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    The first year for the 4L80E was 1991. If its in a gas engine truck it is run off of the same computer as the TBI system. If it's in a diesel engine truck its a seperate computer up until 1994. 94 and after the diesels computer controls the engine also. And by the way the I believe the 700r4 is a 4l60e by 1991 and they are also computer controlled.

    The diesel stand alone computers are very hard to find - they run from 600 up. (1991-1993 only)

    The gas engine 350/454 TBI/4L80E controllers (for a 3/4 or 1 ton) are pretty easy to get ahold of they run from 200 up. You need to verify the computer model number to make sure somebody is not just telling you it runs a 4l80e, they are different. (1991-1995) (research the internet) (Vortec engines also use the 4l80e from 1996 to present)

    Aftermarket stand alone computers are pretty easy to find, but they run 900 and up to about 2000. You can find them used starting around 600.

    And you still need to have a correct form VSS signal, a correct form engine speed/RPM signal and a correct form TPS (throttle position sensor) signal. Those are the minimum signals for any computer to run the 4l80e.

    I have read methods of driving the 4l80e solenoids and TCC using only switched contacts. In theory it should work but I have never tried that route. I do have a spare 2wd 4l80e that I plan to try out a aftermarket TCI stand alone computer on as well as the manually switched method (someday project)

    I have used the 454TBI/4l80e factory setup in a 79 K5 and it worked well. I am currently installing a 1992 6.5td/4l80e into a 78 suburban.
     
    Last edited: May 6, 2005

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