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sm420! i need help!

Discussion in 'HardCore Corner' started by jayoung, Feb 15, 2004.

  1. jayoung

    jayoung

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    i want to put an sm420 in my cruiser. is there any difference between 2wd and 4wd sm420's? i also plan on just adapting my 3-speed transfer case to the sm420.

    thanks in advance for any help

    jeff
     
  2. CruisinGA

    CruisinGA

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    Uh, have you read any tech articles?
    Read them. Read them again. Now read them once more....

    Other than some rare instances, there is no such thing as a 4wd SM420. Even then I think the transmission is the same.

    Read the articles and come back with specific questions. Theres no need for me or anyone else to retype what has already been said.
     
  3. jayoung

    jayoung

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    thats what i thought but the guy at classic cruisers told me differently. i just wanted to be SURE before i spend a bunch of money.

    thank you!
     
  4. 73lndcrsr

    73lndcrsr SILVER Star

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    Take a look at the extreme bends installation article. It is very thorough.

    www.extremebends.com
     
  5. MARKUS118

    MARKUS118

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    Are you sure he didn't mean a sm465 ::)? Those were available in 2wd and 4wd.
     
  6. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    Could have.....
     
  7. phlyfish

    phlyfish

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    sm420 is the same for 4 wd adn 2 wd. the sm465 is different. On a 2wd truck w/ a sm420 (pre 68) you may find a closed bell that houses the universal joint. It is no big issue to get rid of.
     
  8. too tall

    too tall

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    I believe there are rare versions of the sm420 which have a higher output spline count than the 10 spline version which you will need. I think this is the only thing you need to watch out for.
     
  9. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    Never heard, or seen what you speak of....
     
  10. theo

    theo

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    Might try searching for Napco. They built 4WD conversions for 1950's GM trucks. That might get you a pic or explanation or how they mated a transfer case to the 420.

    If it's anything like the 465, they just cut the threads off the output shaft and slipped the TC input over it. Don't know for sure, though.
     
  11. theo

    theo

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    Just talked to a friend who owns a '54 Chev with original 4WD. The transfer case is divorced. That means a 420 is a 420. The transfer and tranny are connected by a short driveshaft, so there was no need to use different output shafts.

    As far as I can find out (which isn't always that far) nobody else did 4WD conversions for GM back then.

    Sorry if y'all already knew this. News to me though.
     
  12. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    Learing is a good thing!

    I know of at least 6 pre 65 chev 4x4's that all have a divorced case from the four speed trans..but that is not everything that was ever out there...
    All the 420's that I have ever worked on or done anything with have all been the 10 spline output...

    :beer:

    -Steve
     
  13. Texican

    Texican s-Moderator

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    Since some of you either have never seen one or don't believe they exist, here is the SM420/Rockwell221 ....stock in the 67 3/4 ton GM's
    Butch
     
  14. Texican

    Texican s-Moderator

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    I spotted this in my secret wrecking yard.......the owner came up one day and needed exhaust on his truck and we swapped. Interesting setup, be very cheap HD stuff if you wanted to run a centered rear axle.
    Butch
     
  15. Texican

    Texican s-Moderator

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  16. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    So,

    Is it for sale butch?

    PM me a price.
     
  17. wngrog

    wngrog SILVER Star

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    THIS is a hardcore thread!!!

    Hey Poser...with Butch, EVERYTHING is for sale :D
     
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