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Best tranny/tcase combo?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by txbartman, Dec 4, 2001.

  1. txbartman

    txbartman 1/2 ton status

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    I actually have 2 questions, count them, 2.

    Rig use: Trail running, mud bogs, 300-350HP engine, some rocks, little highway driving if any

    1. What is the best (with economics in mind, guys) tranny/tcase combo for this rig? I was thinking TH400/NP203.

    2. Could a D44 front axle open diff stand up effectively to this setup with 38s or 39.5 Swampers?

    Thanks in advance...

    Brian
    Check out <a target="_blank" href=http://tx85gmcguy.alloffroad.com>My Jimmy</a> with all her projects!
     
  2. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I assume you will be running a mild Big block or a healthy Small block from the HP figures. The best combo is a little tricky especially when you weigh cost vs. performance. The big question is if you want to go auto or manual. I like autos (my preference) and since you stated a 400 that is a good stout tranny for off-road use (little or no highway with those tires). In stock form the 400 is about as stout as they come but eats some HP and has a high (low numerically) first gear. A 350 can be made pretty bullet proof too but it takes $$$. As far as the t-case, alot will depend on the gears. A 205 is a wise investment if you are going the big tire route, but you suffer with the highest (lowest numerically) low range (1.96:1). As long as you aren't going to be doing much highway driving, you can compensate with gearing. My suggestion is the 400/205 or built 350/205 combo. If you want to go overdrive (which is kind of unnecessary on a trail rig), go with the 4L80 or built 700r (Raptor style), with the 700 being easier (supposedly) to mate to the 700 than the 4L80.

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot> click here </a>
     
  3. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    400/205! Nothing stronger!

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  4. zakk

    zakk 1/2 ton status

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    i run a 350/203 P/T behind my tired old 400. it works fine, puts out ~110 HP @ the wheels. I would step up to a D60 with 38's+ The weight of the trucks + Big Tires + Actual manuvering will not add up to off road sucess IMHO

    -zakk

    '77 1-Ton K5

    [​IMG] CK5's MOAB 2002 OR BUST!! [​IMG]
     
  5. txbartman

    txbartman 1/2 ton status

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    I figure to run the D44 until it breaks and then replace with a D60. Or replace sooner if opportunity presents itself.

    Brian
    Check out <a target="_blank" href=http://tx85gmcguy.alloffroad.com>My Jimmy</a> with all her projects!
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    <blockquote><font class="small">In reply to:</font><hr>

    400/205! Nothing stronger!

    <hr></blockquote>

    NV4500/205...[​IMG] Stronger and a better crawl ratio plus overdrive.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  7. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    I'll scond rene on the NV4500/205 It you aren't doing any highway driving go the manual route. Much better ratio's and you can compensate with gearing because of the OD. Great setup and even with big meats you can crawl all over anything.

    What? You think the hole is too deep? Lemme see...
    1985 GMC C-10 Shortbed
    1984 Chevy K-5 Blazer
     
  8. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Well, you got me there! But that is for you guys that have the thick wallets! [​IMG]

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  9. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    My rig will always be highway compatible to some degree...so I gotta have OD. To me, the ultimate set up is a T700 Raptor in front of a 203/205 ORD doubler. =)

    J


    See the on-going build up of my '85 Jimmy! http://community.webshots.com/user/jekbrown
     

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