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Axle Ratio

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mikeyg79, Mar 28, 2003.

  1. Mikeyg79

    Mikeyg79 Registered Member

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    Does anyone out there know what gears came in an '84 K20HD?
    I love my truck and all, but high way driving is killing me with gas- I got enough gears for the wheeling I do, so a shift to a higher set wouldn't hurt too much.

    Mikey
     
  2. heavy4x4

    heavy4x4 1/2 ton status

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    98% chance it's 4.10's....because it's the HD. What tranny do you have?

    Yeah, 4.10's are pretty low for stock size tires (setup in the trucks because they're meant for towing and load-hauling) so I guess you'd see better gas mileage and lower cruising rpms with 3.73's. I wouldn't go numerically lower then that, though.
     
  3. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    You could put some bigger tires on it[​IMG]

    Just a thought
    John [​IMG]
     
  4. Mikeyg79

    Mikeyg79 Registered Member

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    It's a 350 SM465 NP208 setup. I already have larger tires on it, but Maine law doesn't allow more then 2 sizes bigger.
    At around 75mph, my 350 is twisting almost 3000rpm.
     
  5. wrathORC

    wrathORC 1/2 ton status

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    245x75r16s probably came on it, or what? What size tires do you have now? You could get away with 31" rubber if you don't get some gnarly looking tires.
     
  6. rick88blaze

    rick88blaze 1/2 ton status

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    sent you an email with the factory GM RPO codes. the email explains how to read them. the code list can tell you what all options and equipment your truck came with. /forums/images/graemlins/thumb.gif

    if anybody else wants them just shoot me a pm with your email and i'll send them to you
     
  7. milspecjimmy

    milspecjimmy 1/2 ton status

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    i ran 35's for quite some time on my jimmy that came with 235/75's on it, and i got pulled over a few times for other things and the tires were never mentioned. i am running 275/85's now, and still no problem, they even look way too small for the truck. i wouldnt worry about the tire size thing, unless you are being an arse while driving the police probably wont even notice
     
  8. Mikeyg79

    Mikeyg79 Registered Member

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    It's spec'd to have 235/85/16. I put on a set of 255/85/16 which is about a 33"
     

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