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Thread: Can a 5.7 vortec be swapped out for a 7.4 vortec.

  1. #1
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    Dec 2019

    Default Can a 5.7 vortec be swapped out for a 7.4 vortec.

    I have a 1996 chevy k1500 4x4 with a bad 5.7 vortec. and I have a 1998 chevy 3500 dually 2 wheel drive with a good running 7.4 big block. Can I use the motor and the wiring harness and computer off the 98 dually and put in the 1996 chevy k1500. Will 7.4l bolt to my 4l60e trans in my 1996 k1500.

  2. #2
    Lifetime Member SS2win's Avatar
    Join Date
    Feb 2005


    There are minor ECM and body wiring differences between the two years but for the most part it will bolt in. I don't know why you'd want to run the 4L60 behind big block but the trans wiring harness can be repinned to work with it. I'd recommend an 0411 swap rather than mess with the black box computer.
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  3. #3
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    Dec 2019


    I don't have a lot of money and this is the only option I have at the moment. I just wanted to no if the harness will be able to swap at the firewall with out having to change out dash boards. I already have the 5.7 vortec out. all I have to do is disconnect harness and computer. I want to put harness and computer out of 98 dually into 96 chevy k1500. The 4l60e is all I got to use because truck is 4 wheel drive. the trans in the dually is 2 wheel.

  4. #4
    Lifetime Member
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    Mar 2006


    You'll likely need a new trans sooner than later, the 60E was never built to handle the TQ of a BBC. Be careful and it may last a while, I'd give the 60E a once-over while you have the engine out regardless.

    You may need to program the VIN of the 5.7 into the 7.4 PCM, not sure what the anti-theft/immobilizer setup is on those year trucks.
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