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Gear Ratio Questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bart, Mar 15, 2000.

  1. bart

    bart Registered Member

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    Location:
    Eastern PA
    I have a 1984 K10 Blazer...the factory parts ID label on the fenderwell lists the axles as AXLE 1G01
    I think these are like 3.08 or something like that. Can someone confirm this?

    The truck has a 305 and NP435 Manual, it's a dog.
    I have a 350 to put in it sometime soon.
    I want to run 33 inch tires and still be able to go 65 without turning 3500 rpm.

    I have an opportunity to buy some complete 3.42 axles for a good price..should I get these or hold out for 3.73's?

    Bob
     
  2. Black89k5

    Black89k5 Registered Member

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    WHat tranny do you have a Turbo 350 or 700 r-4?
     
  3. '73 K5

    '73 K5 1/2 ton status

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    First of all I seriously doubt you have an NP435 gearbox unless you jacked it from a Ford. The Chevy 4 speed equivalent is a Muncie SM465.
    I also have an SM465 and I am planning on buying a set of 33's this summer. Since that tranny is a wide-ratio type, it always feels like you're in the wrong gear. Thats one of the reasons it makes your truck slow. By raising your RPM with new axle gears, it will help make your Blazer a little easier to drive, even with the big 4 speed.
    I think a lot of people would agree that a perfect gear ratio for highway and offroad driving would be 4.11 gears for 33 inch tires. At 65 mph your RPM shouldn't be much above 2800 or so. Don't get the 3.42's. If you drive on the highway a ton, go for the 3.73's. If not get the 4.11's like I did.
     

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