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Final drive ratio question?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Emmettology 101, May 30, 2000.

  1. Emmettology 101

    Emmettology 101 3/4 ton status

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    Ok, I have a question for all you final drive ny=umber crunchers out there.

    Which would be a better set-up in low range?
    (both vehicles being Jimmy's, both running TH350 trannies, and both running 35's)

    1) NP203 with 4.56 gears

    or

    2) NP 208 with 4.10 gears

    or are these setups really similar?

    Thanks
    P.S. I believe the TH 350 has a 2.72:1 first gear.



    Mike
    82 GMC Jimmy "Emmett" "Built for function, not for beauty!"
    IN TOO DEEP Off-Road Club
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Asuming the tranny has the same 1st gear ratio in both trucks.
    203 (2:1 low) x 4.56 = 9.12 x 2.72 = final drive of 24.806:1

    208 (2.6:1 Low) x 4.10 = 10.66 x 2.72 = final drive 28.995:1

    Really when it came down to it driving them you would probably never be able to notice the 4.1 rev difference.
    Personaly I would go for the 203 because it is stronger.

    Diging it in the dirt with my K5's
    Grim-Reaper
     
  3. Emmettology 101

    Emmettology 101 3/4 ton status

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    Would you happen to know the 2High ratio in these t-cases?

    Mike
    82 GMC Jimmy "Emmett" "Built for function, not for beauty!"
    IN TOO DEEP Off-Road Club
     
  4. Emmettology 101

    Emmettology 101 3/4 ton status

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    Oooopppppssss...... The TH350 first gear is 2.52:1 not 2.72:1

    Sorry......

    Mike
    82 GMC Jimmy "Emmett" "Built for function, not for beauty!"
    IN TOO DEEP Off-Road Club
     
  5. Blazer1970

    Blazer1970 1/2 ton status

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    High range is 1:1 in ALL transfer cases.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  6. Emmettology 101

    Emmettology 101 3/4 ton status

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    Thank you!

    Mike
    82 GMC Jimmy "Emmett" "Built for function, not for beauty!"
    IN TOO DEEP Off-Road Club
     

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