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Thread: Identifying LS that is already installed and complete

  1. #1
    Join Date
    Sep 2014
    Posts
    17

    Identifying LS that is already installed and complete

    Howdy,

    LS newb here with a GMT400 truck that already has an LS swapped into it. Can't seem to see casting #'s on the back of the block no matter how hard I try; having a better idea of exactly where I need to look would be good - might be some crud covering and I'm just not scrubbing the right place. Very limited access and visibility.

    Also head #'s appear to be 803 at the corner?

    Block is aluminum. Intake is the black plastic style that appears to be LS1 type but not sure. Throttle body is 3 bolt and DBC.

    Accessory drive system appears to be aftermarket.

    Engine is *supposed* to be an LS1 but the seller is shady so I'm not confident in his claims.

    Harness is a hackjob nightmare and it seems there's boobytraps everywhere waiting to break if I attempt to lay across them to search for casting numbers...



    Thanks in advance,
    Richard

  2. #2
    Join Date
    Sep 2008
    Location
    Hope Mills, NC
    Posts
    676
    What is the part # on the intake manifold, exact casting number on the head, as well as block casting #? Gonna have to get down there and search. Are your valve over volts perimeter style or centerbolt? If it appears all stock I bet you have an early style ls1 under the hood.
    2005 GMC RST *sold
    2006 Silverado SS with nawz

  3. #3
    Join Date
    May 2007
    Location
    Oak Forest, Illinois
    Posts
    276
    If the PCM came from the same car as the engine then it is a 98 LS1. As far as I know that style PCM was only used on the LS1 cars in 98.

    Jeff
    98 GMC RCSB 2wd, 100% internally stock 305, w/twin T-3 junkyard turbos,Ramjet intake w/42lb inj,12200411 PCM. 4675lbs w/me in it. Best time in 5 passes 13.01@110

  4. #4
    Join Date
    Sep 2014
    Posts
    17
    Thanks; any hints on accurate locations for the numbers I need to look for - to save unnecessary disassembly?

    The valve covers are indeed perimeter bolt style, not center.

    I would like to think that's the PCM that came with the engine, but have no real idea of knowing for sure. The guy that allegedly did the swap wrote on the receipt that the engine was from an 02 Firebird, but the guy I bought the truck from hinted that he had some issues with the shop. Sounds like a lot of b.s. soap opera, seller claimed he personally bought a complete wreck for a donor and that it was an 02 Camaro hit in the rear. There's paint marker on so many of the parts that I'm pretty sure both of them are full of it, unless they picked up a wrecked donor car that already got a bunch of parts from the boneyard, seems unlikely.

    Richard

  5. #5
    Join Date
    Sep 2008
    Location
    Arizona/Utah
    Posts
    3,939
    Aluminum block is a good indicator it is an LS1 only I tiny percentage of 5.3s were made with the aluminum block. Also I believe the 803 heads only came on 98-00 LS1s. Which also leads me to believe its a early Ls1. The intake is indeed LS1. The 98pcm also a give away. A 02 should have 241 heads.
    Last edited by kerrige; 10-02-2014 at 02:13 AM.
    ECSB 2kSierra 2wd 4.8L-K&N-HPtuners-Calspeed LT's-Magnaflow-Tahoe20's-HankookRH06

    waiting to go in... 3.90s, 214/220cam

  6. #6
    Join Date
    Sep 2014
    Posts
    17
    Thanks everyone. I'll try to make the effort soon to locate some of the casting numbers but it's a major pain with everything in the way, instead of the engine out on the ground, no accessories, etc. The wiring harness in this truck is so cobbled-together that I can't even lean across the engine to get a peep mirror on the back of the block, for fear of ripping the wiring apart as it's run all over the place, no slack in it, taped, crimped, etc. Friggin hacks!

    Richard

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