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sm420 in the flattie

Discussion in 'Flat Fender Tech' started by brandon533b, Jun 1, 2010.

  1. Jun 7, 2010
    brandon533b

    brandon533b Member since 2007

    Yakima,WA
    Joined:
    Mar 2, 2007
    Messages:
    220
    well if i mess with the tranny, i'll go to thechev 4 spd. thanks though.
     
  2. Jun 18, 2010
    Zup

    Zup New Member

    Joliet
    Joined:
    May 27, 2007
    Messages:
    38
    I have SM-420 swap with Dana 20. Where can I get a speedometer cable long enough to run from the transfer case to my speedometer my current cable is not cutting it. Another thing is what does everyone use as a cross member for the SM-420 and Dana 20 swap. I'm currently using the stock cross member but is there something better or more solid and simple out here?
     
  3. Jun 18, 2010
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
    Joined:
    Jul 30, 2003
    Messages:
    8,513
    these are all Jeep part numbers; should be available at any of the places that sell Jeep parts.
    5351775 - 64.5" long
    5351776 - 80" long
    5351777 - 69" long
    5351778 - 60" long
    measure yours (overall length)
    one of those should fit the bill.
     
  4. Jun 18, 2010
    Mcruff

    Mcruff Earlycj5 Machinist

    Albertville, AL
    Joined:
    Sep 22, 2002
    Messages:
    5,349
    Even one that is junk has useable parts. I bought a junk one for $10 a few years ago, the lower gears had sit in water the whole upper shaft of gears was good along with the tower and bearing retainer. These transmissions are all over around here.
    I bought 7 of them 3 years ago for $75 a piece. Unless it has set in the rain the chances of it needing anything other than a general rebuild are slim and none. I doubt with a v6 or small v8 you would ever tear one of these up in a jeep, your entire drivetrain would go 1st. These transmisions were installed in eveything from dump trucks, school buses, motor coaches, pickup trucks, city buses and so on, there were literally hundred of 1000's of them made. Getting a spare one for parts is easy, as far as needing 6 of them to make 1 good one I doubt that very seriously, 2 maybe 3 at most. The 7 of them I picked up were all out of bread trucks (with very high mileage) and every one of them was perfect.
     
  5. Jul 7, 2010
    54cj3b

    54cj3b Member

    evergreen colorado
    Joined:
    Jul 7, 2010
    Messages:
    236
    I put a 4.3 with a sm465 along with a dana 18
    engine fit perfectly trans now that was no picnic lots of cutting of the floor to get it to fit right was even surprised to find the orig shafts still fit but still beefing them up anyways this swap was not fun to do by yourself like I did
    didn't think it was going to go in now that pain in the azz is done now its the hydraulic clutch and exhaust and wiring it all up
     
  6. Jul 8, 2010
    windyhill

    windyhill Sponsor

    PA
    Joined:
    Nov 4, 2006
    Messages:
    1,502
    Go with a t-18 out of a ford. easier to rebuild, plenty of parts much lighter then the sm465. I did one im my cj3b and love it, I've also done the sm465 and it's much more of a PITA to rebuild and is really big and heavy!
     
  7. Jul 8, 2010
    54cj3b

    54cj3b Member

    evergreen colorado
    Joined:
    Jul 7, 2010
    Messages:
    236
    big n heavy doesn't tell the real truth its a boat anchor ,my 3b sits a inch lower now
     
  8. Jul 10, 2010
    bnorth10

    bnorth10 Wicked Willys Customs

    Joined:
    Feb 27, 2007
    Messages:
    128
    Just finishing up the one in my 52 M38A1 and w/ small block and overdrive. Salivating, imo best bang for your buck for durability, size and low range and sure beats the ol 3 speed even though my t90 has survived 15yrs against my small block
     
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