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Sm420 T Dana 18 Plate Adapter?

Discussion in 'Early CJ5 and CJ6 Tech' started by Mr Vaughan, Feb 8, 2021.

  1. Feb 8, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

    Central City, NE
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    Why can't there be a 7/8" adapter for the sm420? if they can do it with an sm465, why can't they do it with an sm420? i don't want to have to either move my transmission/engine forward or modify driveshafts. the sm465 adapter is $30 more, and is only 7/8" thick, with a new output shaft. is it not possible to make a new output shaft for a 420, or what?
     
  2. Feb 8, 2021
    timgr

    timgr Eppur si muove. 2021 Sponsor 2020 Sponsor

    Medford Mass USA
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    Probably does not make economic sense to make such a kit for the SM420. Call Novak and ask them.
     
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  3. Feb 8, 2021
    47v6

    47v6 junk wrecker! 2021 Sponsor 2020 Sponsor

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    Its because the front yoke for the D18 won't clear the transmission case.
     
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  4. Feb 8, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

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    it all makes sense now.
     
  5. Feb 8, 2021
    47v6

    47v6 junk wrecker! 2021 Sponsor 2020 Sponsor

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    Yeah, its annoying, but it just doesn't fit unless it has that offset. BTW, don't ever make decisions based upon driveshafts. These are really easy to fabricate or have made for a reasonable cost compared to the insane amounts of compromise to keep them.

    Also, the SM420 hasn't been made since 67 commercially or for the military for some applications until 85 or so. There are other transmissions that have more parts available that are similarly qualified such as a T18.

    There are real problems getting the correct synchros for whatever era 420 you get. The early ones like mine don't even have a front seal, so you're going to leak gear oil if you're downward to any great degree.

    A 465 is a better GM choice, but its enormous.
     
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  6. Feb 8, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

    Central City, NE
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    yeah.
    i'm afraid that i can't take off much of the rear without causing issues, as there's not much extra driveshaft.
     
  7. Feb 8, 2021
    Rich M.

    Rich M. Shoe pusher

    Maryland
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    Listen to me..the international version has a few quirks mostly related to bellhousing mounting. All the guts fit into a common Ford T18 case. If you are fortunate it's a low first T19. The adapter works for T18/T19 either way the price is right.
    Philadelphia
    Haggle to $100
     
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  8. Feb 8, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

    Central City, NE
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    don't see what you posted rich, the post is gone. a t18/19 might work
     
  9. Feb 8, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

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    one more thing that might not work with the T18: i wanna put a 4.3 in. don't know if it bolts up to a GM engine, but if not, that puts a stop on it.
     
  10. Feb 8, 2021
    timgr

    timgr Eppur si muove. 2021 Sponsor 2020 Sponsor

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  11. Feb 8, 2021
    Fireball

    Fireball Well-Known Member 2021 Sponsor 2020 Sponsor

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  12. Feb 8, 2021
    timgr

    timgr Eppur si muove. 2021 Sponsor 2020 Sponsor

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    Ha! There's an echo in here!
     
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  13. Feb 8, 2021
    Fireball

    Fireball Well-Known Member 2021 Sponsor 2020 Sponsor

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    Rats. I was too slow!
     
  14. Feb 8, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

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    where do i get a ford T18? if it's cheaper, and fits better, i'm all for it.
     
  15. Feb 8, 2021
    Fireball

    Fireball Well-Known Member 2021 Sponsor 2020 Sponsor

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    Ford 3/4 ton or up pickups from the mid 60's up into the 80's. Doesn't matter if it's a 2wd or 4wd. The adapter will work with either.
     
  16. Feb 8, 2021
    boopiejones

    boopiejones I can’t drive 55

    California east bay
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    My Jeep has an sm420 with a d18. It was installed by the prior owner, but I have some of his old documentation including his measurements for the driveshaft. Let me know if you are interested in any of that and I’ll see what I can dig up.
     
  17. Feb 8, 2021
    47v6

    47v6 junk wrecker! 2021 Sponsor 2020 Sponsor

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    The front driveshaft on all old jeeps are worn out. The splines moving back and forth wear out the slip yoke and splines till they wobble real good and get out of balance on 4 high. Making a new driveshaft for the front is a piece of cake. Buy the parts, some DOM, clock them right, tack, temp install to true it up and weld it. It’s pretty easy.
     
  18. Feb 8, 2021
    garage gnome

    garage gnome Rust polisher 2021 Sponsor 2020 Sponsor

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    Yes, a T18 can be adapted by using junkyard parts. You'll need a Ford input shaft, which can be bought new off Ebay. If you find a Jeep T18, it will have the transfer case adapter already. If you can't find a large hole D18, you can put D18 guts in a D20 case.
     
  19. Feb 8, 2021
    Bigdaddy13

    Bigdaddy13 Member 2021 Sponsor 2020 Sponsor

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    I could use this info. I’m also running a 198 v6 (i think thats what you’re running?).

    thanks!
     
  20. Feb 8, 2021
    Rich M.

    Rich M. Shoe pusher

    Maryland
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    Screenshot_20210208-184137~3.png
     
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