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Thread: 6.2/6.5 Cylinder Block Date Code

  1. #1
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    Arrow 6.2/6.5 Cylinder Block Date Code



    What month, day and year was this 6.5L block cast?

    To answer the question... All of the 6.2L/6.5L cylinder block casting dates up through November 2001 used 4 digits. The reality is though, that GM stopped casting these cylinder blocks well before the November 2001 hand-off to AM General.

    The beginning letter (A, B, C, etc) indicates the month; A=January, B=February, etc.; the "C" in this case tells us it was March. GM didn't use some of the letters of the alphabet in any casting codes because of a possible confusion with a number, such as the letter I or O. The next two digits in the above block code shown indicate the day of the month that this block was cast; in this case the "06" indicates the 6th day of the month. The fourth digit indicates the year in which the casting was made; in this case 199"6", because we know it's a pre-oil spray 6.5L block. So this 6.5L block was cast on March 6, 1996.

    With just one digit indicating casting date year, you have put the block into context with what we know the 6.2L/6.5L production to get the right year.


    Jim
    Last edited by More Power; 01-02-2023 at 10:23. Reason: answer the question...

  2. #2
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    March 6, 1996

    is my guess
    1994 K1500 Silverado ext cab short box
    stock L56 6.5 TD, F intake, 4L80E, 3.73 gears
    10149599 block, D-Tech PMD on 5288 pump
    Goodyear Wrangler silent armour 265 75 R16 E Pro Grade
    Bushwacker fender flares
    410,000 km

  3. #3
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    Must be a trick question, but that would be my guess, as well. Did we win the prize?
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  4. #4
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    Good job! You win an official "attaboy".

    What can you tell us about the following number?


  5. #5
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    It verifies a 6.5L casting. After the 599, and before the 929 and 506, with no piston spray, and no heavier bore casting in the rear cylinders. Probably the "weakest" of the non-spray castings. A good choice for N/A economy use, as it a little lighter than other castings.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  6. #6
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    I would probably have guessed 141 suffix was BETWEEN 929 and 506, but may well have been wrong, it wouldn't be the first time.
    1994 K1500 Silverado ext cab short box
    stock L56 6.5 TD, F intake, 4L80E, 3.73 gears
    10149599 block, D-Tech PMD on 5288 pump
    Goodyear Wrangler silent armour 265 75 R16 E Pro Grade
    Bushwacker fender flares
    410,000 km

  7. #7
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    I too thought that the 141 number was between the 929 and 506. The only thing I've ever seen a 141 in is an early '96 without the cooling upgrades. As best I could tell the 141 was almost identical to the 599 except for the oil pressure sender location and a couple of minor details. I also thought that the 929 number was the GM goodwrench number that was equal to the origional 599?
    white '93 K2500 started it all..
    red '94 K3500 old faithful
    black '93 K3500 daily driver
    '83 G20 conversion van
    '74 C65 truck diesel conversion...

  8. #8
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    I have a 929 block at the machine shop right now that is a 1995 casting out of a 95 truck. So I would have to argue that the 141 came after the 929...

  9. #9
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    '141 is a 96 block with the 3/8" cooling lines. Has the boss in the back of the block that is just like a Hummer/Gvan turbo engine, but nothing is drilled or tapped (yet).

    Have one identical to it sitting wrapped up.

    Just like a '599 or a '929, just another year, but with the '97+ capabilities as far as rear mounted turbo.

    I'd wager a bet that this block was also used in Hummers that used the turbo starting in '96, but w/o the piston oil spray coolers.

    J

  10. #10
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    The casting numbers are just that, casting numbers. The castings overlapped, depending on application. GM didn't stop one casting, and start another. Newer castings were started and implemented, while previous castings were still in production. If this block was a van/HMMWV application, that's likely what happened. Older casting in a later model. The order of casting I was refering to was the actual full number. The 141 castings began before 1996, and other castings were made during that time.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  11. #11
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    In my experience with casting design and manufacture, it is unlikely that multiple castings were made at the same time. Some new old stock might have been used after a new one was introduced to foundary production, however. When casting changes are made, the tooling gets modified making it very difficult to go back to the older configuration. On occasion, an insert in the tool can be used to allow multiple design configurations, but this is costly, lowers precision and opens the door to parts with the wrong features. Looking at these blocks, I can see no evidence of inserts being used.

  12. #12
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    This block was sitting in Peninsular's shop the day we were there. It was removed from a motorhome with more cylinder taper than I've seen in a 6.5. This was due (we were told) to a collapsed air filter, that allowed the engine to ingest dirt for quite some time. Like others I've seen with washed-out cyls, #6 & #8 were the worst, though all eight holes were trashed.

    Jim

  13. #13
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    Default 1995 Van

    My van is a 1995 one ton was the block use in the van's somwhat better then the 6.5l in a P U truck? I will get the casting number later today when i pull out the #8 glow plug to see if there is water in the hole

  14. #14
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    Quote Originally Posted by ronniejoe View Post


    Does this mean December 17, 2003?
    No, the first two digits are the month, the next two digits are the day of the month, and the letter indicates the year in which it was cast. So, a "03 17 L" would be March 17, 2004.

    H = 2001
    J = 2002
    K = 2003
    L = 2004
    M = 2005
    N = 2006
    P = 2007

    Jim

  15. #15

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    Hi, I have a J108 and a M238, both 506's and after a lot of searching i cant find any indication of a year. Anybody willing to shed some light on the subject. please

  16. #16
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    The last digit in your date codes are an "8", which indicates a year that ends with an "8". It must be 1998.

    Jim

  17. #17

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    Thank you. Was that year any good? I am planing putting one in my 22.5 ft sea ray and the other in a 04 dodge ram 1500 SLT, am sure glad i found this forum

  18. #18
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    The late 1996-2000 GM manufactured blocks did crack somewhat more frequently than earlier GM blocks. Not all of them cracked, but...

    Pull the center 3 main caps and look for cracks originating at the outer or inner bolt holes in the main webs. If yours are crack-free, you might be OK.

    Jim
    Last edited by More Power; 07-13-2009 at 14:09. Reason: add to

  19. #19
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    My 929 block that is soon ready for the DaHoooley is numbered "F154"
    June 15 94 ??

    Non squirt, Large outer bolt.


    Missy
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2007 Chevy Avalanche
    THIS IS BOW TIE COUNTRY

  20. #20
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    Quote Originally Posted by Robyn View Post
    My 929 block that is soon ready for the DaHoooley is numbered "F154"
    June 15 94 ??

    Non squirt, Large outer bolt.


    Missy
    Yup... June 15, 1994.... Should be fine. If a well-seasoned block is crack-free now, it'll likely remain that way.

    Jim

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