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Thread: looking to swap a 5.3 engine and trans to an 85 p/u

  1. #1
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    Question looking to swap a 5.3 engine and trans to an 85 p/u

    Hello! I am looking to swap an 5.3 eng and 460le trans into my 85 4x4 stepside. Has anyone on this forum done this? Any info is appreciated. I already have drivetrain, gas pedal, ecm, mass air flow sensor. I am looking at speartech or s&p for the wiring harness and reprogramming. Anyone know if someone makes long tube headers for this? Does anyone have suggestions about running a blazer gas tank vs the stock twin tanks? thanks in advance for any help or ideas.

  2. #2
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    if i was you id go with a Nelson Performance wiring harness. its 650+ shipping vs the S&P wiring harness is probably 900+
    2008 GMC CCSB 6.2/6L80e swap
    Gen IV 5.3/60e swap 1994 ecsb W/T

  3. #3
    Join Date
    Aug 2006
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    192
    go with speartech or nelson if you can't do it yourself....s&p is expensive.
    Some guys use fbody long tubes, I used s&p mid length, can't complain, they still look brand new after over a year.
    I had twin tanks , got rid of drivers side, only using pass. side. Holds enough to cruise on saturday...lol
    86 C10 6.0/4l80e

  4. #4
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    hey pcmcobra,just wanted to know how long it took u to complete your 6.0l swap? are u running a/c? do u have any pics? what wiring comp.did u use? or did u use stock wiring harness? as far as motor mounts 5/16 or 3/8? anything i should or should not do? SORRY FOR ALL THE ?????????????

  5. #5
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    Aug 2006
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    192
    um, it took a few months...in my "rare" spare time after work and some weekends.
    No ac...stock wiring harness reworked by speartech, stock ecm tuned by local shop.
    z28 electric fans, motor mounts from carshopinc.
    Finally!!! 6.0 POWAH!!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network
    86 C10 6.0/4l80e

  6. #6
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    Dec 2009
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    pcmcobra,thanks for all the info&pics its really a big help looking forward to swap in spring.again sorry for all ??????? it was truly a big help.

  7. #7
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    keniff,thanks for the info on the harness.

  8. #8
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    This was info that was passed down to me. I though i would share his post with you.

    header from summit part# SUM-G908 $153.93 they are shorty headers fit 99-04 truck requires slight mods to PASS side rail , i welded round stock to the underneath of the rail where i modifed it -you can use stock manifolds if you wish but make sure there the non EGR TYPE they will hit the frame where the EGR pipe mounts to on the manifold the header claim 15hp but do sound great

    trans-dapt 4572 engine mount adapters $47 seems to put the engine nicely against the firewall with plenty of clearance, they're from summit as well
    fuel pump airtex fuel pump E3270 provides plently of PSI $79.99 AutoZone
    fuel pump lines, people spend money here for no reason go to a junk yard and get lines from a pickup or tahoe 99 -2003 from the rail to the tank and only modify the part where it
    goes into the tank use a 87 - 91 EFI sending unit
    make sure you use the EVAP lines if your using the charcoal canister ! im not so i got rid of it and plugged the hole in the intake but tapping it out with 1/2 tap and use a short bolt!
    oh if you remove the EGR stuff of a 99-02 engine just remove the the plate that screws to the intake from the flex steel pipe and cap it dont buy one from GM for $30 takes 10 min to mod
    top rad hose of a 2001 silverado $17.99
    temp switch adapter 1/4 3/8 1/2 about $18.00 S&P
    harness mods $212 including the OB11 i used a guy from ebay i was a little worried but it works great oh by the way i dont have A/C but others do i have his email so message me if you want it
    ECU mods removing egr , rear O2s ,removing VATS, etc etc etc $75 i have his email too its a different guy
    there are a few other mods like i moved the battery to the drivers side make a better fit IMO use a diesel tray there cheap , i used a KN filter out of a 2001 truck i got it for $75 used made a brackets works nice!!!
    if your running cats your gonna have to make some mods to the factory 99-04 Y-pipe OR if your not running them you can do what i did i made my own flanges and made the pipe extentions from each header i put the front O2 bungs in each pipe extention and i was good to go!!! i cut my own gaskets from exhaust gasket sheet with the aluminuim works great no leaks
    you might have to move your trans crossmember back and mod your drive shaft i cut mine 1 3/4in cost was $55
    im using a 91 blazer/burb speedometer takes care of the the 4l60e /4l80e electronic speedo
    Last edited by 87OldYeller; 01-03-2010 at 12:52 PM. Reason: forgot something

  9. #9
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    seems simple. good luck with the swap.
    if you dont want to have a harness made get a stock harness an rework it yourself or send it to Nelson Performance an have it reworked for 450.00 i believe.
    a lot of people are running LT headers designed for the LSx swap in an OBS thanks to a sponsor on here.
    theres a few options on running an AC..you just have to decide what you wanna do.
    im keeping my cruise/AC/stock gauges, ill be adding a transmission temp gauge though...im going to have my driveshaft high speed balanced. i hope to start putting everything in the truck pretty soon an start modifying anything i need.
    2008 GMC CCSB 6.2/6L80e swap
    Gen IV 5.3/60e swap 1994 ecsb W/T

  10. #10
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    Dec 2009
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    Alabama
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    Last edited by 87OldYeller; 01-03-2010 at 06:39 PM. Reason: need to add info

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