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Np 203 transfercase

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  • Np 203 transfercase

    I am wondering if I can use a front axle assembly out of a 73 3/4 ton power wagon with lock out hubs in place of my existing axle that is in a 75 3/4 ton power wagon that is a full time axle assembly. I know they make conversion kits but I already have this axle in a parts truck, and I am not sure what all the conversion kit includes from full time 4x4 to part time 4x4.

  • #2
    You will need to leave the hubs "locked" or the truck won't drive (unless its in LOC position). There is nothing to gain by switching axles, assuming yours isnt broken.

    The NP203 was designed to operate with all 4 wheels connected at all times, hence full-time. It has a diffential in the t-case to allow front & rear driveshafts to rotate independant of each other.

    Some say the earlier axle won't give the correct driveshaft angle when used with the later married t-cases.

    Bucky

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    • #3
      Very helpful thank you. I bought the older truck for parts mainly a rebuilt 1972 440 that I am putting in mine. But I am also transferring a 8" lift kit as well. The reason I was thinking of using the front axle from the 73 is there is a spacer that is between the steering arm and the steering knuckle and I can't seem to get it to come off, not sure why. The spacer is part of the 8" lift system and I have to have it. Any thoughts?

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      • #4
        Np203

        Not all NP 203s are constantly locked . Where this idea comes from is weird . The np203 in my Chev is not constant , and I have one from a jeep truck that is not locked either . I have 4 low , 4 low locked , 4 high and 2 high .
        Why not jack the truck up with all four wheels off the ground , put the trans in neutral , and try your transfer case shifter in the 4 high position and then try shifting it into another position . just turn the rear driveshaft by hand while doing this.
        There may be a shift position where the front shaft does not turn .

        Worth a try

        Bruce

        yes there is a differential in the NP203 and I love the thing . My front differential is limited slip - so I drive the truck in 4 low unlocked when I am trying to turn in a tough spot and 4 low locked when I am climbing or need equal power to all 4 wheels . Stuff binds up and tends to break if you have the case locked and are in a tight turn .

        edit - just did a search and came up with a quote from a transmission shop - basically there are 2 versions of the NP203 and Ford , chrysler and GM used both ... took some searching to find - high impact transmission was one but there are others who say the same thing .

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        • #5
          Bruce,
          Would your Chevy happen to have a 4-speed? What year?
          Thanks,
          Bucky

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          • #6
            Chevy information

            It has a turbo 350 , 77 or 78 trans and transfer case . 85 one ton axles - dana 60 front , with a power lock out of the rear of some old ford , and a corp 14 bolt rear . I think the 203 has 27 splines , the jeep one I have is 32 spline ( which makes no sense ) because international and chev are the only makes than ran 32 spline as far as I know . Ford used 31 and most Dodge was 23 . Manual trans are mostly 10 spline except in later years when a few used 32 spline . swapping the input is quite simple .

            Bruce

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            • #7
              Thanks,
              My dad bought a new Chevy 1/2 ton short-wide back in 75. It had the "new for industry fulltime 4x4" as it was sorta advertised back then. Actually 350 engine ( burned Regular gas because he got the >6000 GVW package) & 350 tranny/203 t-case, 3.73 geared half ton axles. It was a good truck,but timing chain would get sloppy enough to wear hole in cover, happened 2-3 times, plus Quadrajet carb drank gas at high rate.

              Bucky

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