sm465 swap

Discussion in 'Chevy/GMC 4x4' started by Romeske, Oct 5, 2009.


  1. Romeske

    Romeske
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    So im buying a 1981 chevy longbed and it currently looks to have a th350 bolted to an np208 t-case.



    I am going to convert it to an sm465 np... t-case. Now i would like to know from yalls experience, what transfer case should i be looking for? Should i look for an sm465 np208 combo or 205? which would be easier and require less modification? Either way im going to an sm465 so no worries about clutch pedal and stuff; ive got all that down.



    Or would it be a better idea to just change out the input shaft on my np208 to the 32 spline and just grab the 4 wheel drive tranny?



    Also, what about mounting? Is there a t-case cross member for the 208? if not is there a way to mount the 465 onto the th350 cross member?



    Any help is appreciated.
     

  2. outalne94z71

    outalne94z71
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    well a sm465/np205 is best preferably one built after 1978 as that earlier one had a 10 spline coupler, the big question is how high do you plan on ever goin?



    a 465/205 married combo is the shortest combo and has big front driveshaft issues once you lift over 6" so in that case a 2wd sm465 and a divorced 205 is the hot ticket or if you want more crawling power you could run a married 465/203/205 doubler setup.
     

  3. Romeske

    Romeske
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    well i dont plan on ever going more than 2 or 3 inches if any from where it is now. Im not making this a monster machine or anything special. Just a little offroad truck for a little play.



    I thought about a divorced 205 but i cant find one, but i do have a huge access to 2wd sm465s. Thats why i thought about it. But currently my main concern is mounting. If i get a married 465-208 then where does it mount? at the tranny or the t-case? if i get the married 465-205, same question?



    Divorced i know i would have to mount it separately, but i wont be needing it to be divorced due to my lack of lifting. Also what about linkages? i heard the 205s linkages werent too adjustable. Is this true or any different for the 208?





    And if anyone can, what about the 465-208 length vs 350-208 length?
     
  4. outalne94z71

    outalne94z71
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    a th350/208 is about 10" longer than a sm465/208



    any married t-case uses a adapter between the two, the early ones used a coupler inside that adapter



    if you are not going for brute strength then a 208 will work you need to make sure you have the right spline count for the 465 you are running, for a 208 you need a later 465 to be able to run it and need a 32 spline 208 the earlier 465's were 10 spline and i know of no adapter to run a 10 spline male output to a 32 spline or 27 spline female input that the 208 would have.



    for linkage a 205 has the shifter bolted right to it where as a 208 uses a floor mounted shifter just like the 241



    personally i would run a late 80's sm465 with the hydro clutch setup and a 32 spline np205, that's as strong as it gets for stock gm parts
     
  5. Romeske

    Romeske
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    alright. Well ya i knew all the spline information. Is it 1980 or 81 that they changed to the long shaft 4x4 465? would you I was thinking a later model 465 was teh way to go because of the 32 spline vs the 10. I just didnt. Ill have to keep a look out on craigslist and such for a good combination. how common is the 465-208 setup?
     
  6. outalne94z71

    outalne94z71
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    its pretty common in the 1/2 tons in the early 80's to find a 208 behind the sm465
     
  7. td14addict

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    i did this swap in February, th350/208 to SM465/205. the first issue you will have is the cross member needs to be moved towards the engine about 6 inches, because of the overall shortness of the combo, your rear shaft needs to be 6 inches longer, and the front needs to be 6 inches shorter. this can get pricey, i went the cheap route scene my truck never goes over 60 KM/h, and got a local machinist to add 6 inches to my rear shaft, i did my front shaft myself. the next issue is in the cab. if you get a 205, you will need to cut the hole where the tcase shifter goes, otherwise you wont get the full range of movement on the shifter and it may pop out of gear when flexed out. if you go with mechanical clutch linkage this is an issue too, hydraulic has no major issues.
    also there is some metal in my the steering column that needs to be ground out.
    theres a walk through on the CK5 website, it helped me a lot.
    hope this helps, if you have any questions, just ask.