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Thread: 6.0 and 4L80 into a 1972 gmc

  1. #1
    Join Date
    Apr 2004
    Posts
    6
    New to the board. I have a 1972 GMC swb 2wd and recently purchased a 2002 6.0L 4L80 combo out of a wrecked 2500hd 2wd. Wondering if anyone has done a similar swap? Looking for someone to give pointers, etc.

    gmcgrands@aol.com

    Mark
    1972 GMC Sierra Grande SWB 2WD 6.0 liter Gen 3, 4L80E, Fatman stage 5 IFS Under construction

    Mark

  2. #2
    Join Date
    Mar 2003
    Location
    San Marcos Texas
    Posts
    4,393
    Hey nice to see you here. I have an '81 with a 5.7L LS1. I think the frame is very similer (if not the same) as mine. I'd be glad to give pointers if you need some.
    2006 Superior Blue Trailblazer SS AWD, Stock as a rock

    Sold: 2002 GMC Sportside Denali front end with a 2002 LS1, FLT level 5, Yank 2600, Trick Turbo, T76, Nelson intercooler, 60LB injectors, Warbro fuel pump, Eaton locker, Magnaflow, 3.42, Nelson Performance Tuning (speed density).

    Sold: 1981 GMC LB RC 1500 2002 4.8L 4L60E 12 bolt 3.73 Richmond Lock Right AC PS Nelson Performance tuning

  3. #3
    Join Date
    Mar 2003
    Location
    San Antonio, TX
    Posts
    11,038
    That's gonna be one badass setup, these engine run forever and like the nos heheh.

    Are you going to use the stock HD harness or make one?


    later,

    allen

  4. #4
    Join Date
    Apr 2004
    Posts
    6
    Farmtruc I have the stock harness, computer, maf, etc, but I think it might be easier with a aftermarket harness. I talked with Painless last week and there in the final stages of testing before they release one. Im doing a frame off on the truck and have the time to wait. Im working on the suspension componets and the bare frame right now. I have this same combo in my daily driver (2002 1500HD 4x4 crew cab. Just wantint to gather any suggestions or pointers for when I get to that point.

    GMCWANTSLS1 I will probably have questions when I get closer. Any suggestions on anything to prepare for or purchase in advance?

    Anyone else done anything similar? Anyone transplant a 6.0L and a 4Ll80?
    1972 GMC Sierra Grande SWB 2WD 6.0 liter Gen 3, 4L80E, Fatman stage 5 IFS Under construction

    Mark

  5. #5
    Join Date
    Mar 2004
    Posts
    17
    I was going to perform a similar conversion on my 70 gmc and decided to back off of it for now. What I learned is that the exhaust won't fit in the frame without either cutting the frame, or finding another exhaust setup. Headers or corvette manifolds will work. The A/C compressor will need to be swapped out as it will not work with the older expansion valve setup. Naturally, you'll have to install a fuel pump, and rig some sort of spedo cable if you are going to use the original gauges.

    I'm looking forward to seeing what you come up with. My frame-off budget just wouldn't let me do the full 5.3L upgrade, so I'm going to put my 383 back in with a 200R4. At least this way I'll have overdrive.

    Oh yeah, I forgot to say that for the newer transmission to fit, you'll have to drill new tranny crossmember holes in the frame. They will need to be 1.75" back from the 350 turbo mounting holes.

  6. #6
    Join Date
    Dec 2003
    Posts
    135
    You can get a Cable X from Abbott Industries for the speedo.About $300 bucks.Real easy to install.


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