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Best Diff's Gear Ratio

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Wolf, Jun 22, 2000.

  1. Wolf

    Wolf Newbie

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    Best Diff\'s Gear Ratio

    I have a 81 Blazer with a 350 that puts out about 400hp. A TH350 trans with shift fit and a np205. I am swaping out the diff's for 3/4 ton running gear from a 79 suburban(dana 44 front GM 14 bolt rear). The diff Gear's in the 79 are 3.73. I what to change them BUT I am not sure which gear is the best to go to. As soon as I get the diff's in place I will be putting on SS TSL/THORNBIRD's 35x14.5x16.5 and a 6' lift. I was planing to go to 4.10. A mechanic friend of mine told me that I would get better performance out of 4.56 Gear Ratio. I am and engine man and do not know a lot about diff's gearing. I do 4wheel on the weekend but I haul my horse into the mountains as well. Can I get some options about which Gear Ratio is the best. thank
     
  2. bart

    bart Registered Member

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    Re: Best Diff\'s Gear Ratio

    hey, what did you do to that there 350 to pull 400 ponies out of it?
    just wondering...
    anyways, about your gears...you say a 350 turbo trans...with 4.56's you'll be running about 2700 something rpm's at about 60-65 mph...you say you tow with this..in the mountains..then 4.56's would give you good power off the line and under load...if you drive on the highway at greater than 70 mph a lot...4.10's may be better...unless you want to go deaf from the roar of the engine! go to www.4lo.com and use the gear ratio/rpm utility or chart there to find out all the details...just ask yourself what will you be doing the most with the vehicle...offroading, rockcrawling, mudding, or just driving on the street...on another note, if you go with 4.56's you can always get 38's on there and not feel like you've got a 6 cylinder under the hood...
     

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