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pulling out a sm465 and putting in a sm420

Discussion in 'The Garage' started by 55Willy, Nov 9, 2003.

  1. 55Willy

    55Willy 3/4 ton status

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    going from a 6.55 to 7.20 granny, is it worth it? also the sm420 is out of a 2wd, what would have to be done to get it infront of my 205.
     
  2. Batmanjr

    Batmanjr 1/2 ton status

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    Custom adapter and it depends on what your time is worth you? /forums/images/graemlins/deal.gif Eventually I want to put a 2wd 465 in front of a 203, to gain the 35 spline output, but maybe that's over kill! /forums/images/graemlins/rolleyes.gif
     
  3. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I don't really think you'd notice the difference. Once you get that much gear, a little more doesn't make any difference. You might notice more than me though.
     
  4. GMCLegacy

    GMCLegacy 1/2 ton status

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    what bellhousing are you planning on running? during my experience, i found that a sm420 bellhousing for a SB did not have the ball stud i needed for my mechanical clutch linkage to work. i think some were on the engine block. personally i dont think it would be worth the hassel, but i do think it would be nice to have reverse one rail closer to 1st/low. good luck
     
  5. kennyw

    kennyw N9PHW Premium Member

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    You need a different bellhousing. The SM465 uses a 5.125" pilot diameter while the SM420 uses a 4.655" dia (or something like that)...

    Then you would need the $700 adapter from Advanced Adapters to mount the NP205. I think the price of that adapter alone would kill it for me. Unless you want to run a divorced T-case that is.
     
  6. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Looks to me like the SM420 only has a 7.05 granny? And a 205 is 1.96:1... So going with that info... final crawl ratios would be:

    SM465/205/4.10 R&P
    6.55 x 1.96 x 4.10 = 52.64 crawl

    SM420/205/4.10 R&P
    7.05 x 1.96 x 4.10 = 56.65 crawl

    Not too sure that little bit would be worth the hassle of finding the correct adapter and BH. Just my .02! /forums/images/graemlins/grin.gif

    -Dan
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Yep, my point exactly. /forums/images/graemlins/smile.gif
     

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