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308 or 373?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Rolled, Aug 31, 2002.

  1. Rolled

    Rolled 1/2 ton status

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    I am looking for some advice on what gears to run in my truck. Keep in mind that this truck will only be used for vacationing and towing a boat or a trailer. It will not be used off road anymore.

    Here's what I have:
    87 K5
    305 (soon to be 454 /forums/images/icons/grin.gif)
    465 hydro
    208
    35 inch tires
    stock 308 ten bolts

    I would like to get opinions on power and gas milage. I need to replace the front (bent) and am not sure if I should just track down another 308 or look for a set of 373 gears.

    If you guys could point out the pros and cons I would appreciate it.
     
  2. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    If you are going to be towing I would go with 3.73. They are just as common as a 3.08...
     
  3. captain chaos

    captain chaos 1/2 ton status

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    35's pulling boat or trailer= 3:73 or 4:10
     
  4. 84K5cedric

    84K5cedric 1/2 ton status

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    You should check out a tire/gear ratio chart such as this one. The 3.08's will give you better highway mileage but for towing a boat/trailer (especially with a 305 and 35's) it may not have much power.
     
  5. Rolled

    Rolled 1/2 ton status

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    Thanks guys

    BTW Does anybody know the rpo code for 373s? 308 is GU4, not sure about the others for 87.

    Heres a realted question: Are the brakes the same on the 12 bolt and 10 bolt? I just took off the rear shoes to put new ones on and replace the wheel cylinders and was thinking that if I go with a 12 bolt and they are different then I should return the parts before I use them.

    Anybody know if the rear brake parts are interchangable?
     
  6. Rolled

    Rolled 1/2 ton status

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    Thanks for the link Micah, thats what I was looking for /forums/images/icons/grin.gif
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    You should be able to transfer the brake parts from one axle to another. In fact, if you're lazy like me, you'll unbolt the whole backing plate and bolt it on the new axle.
     
  8. BLUESMAN

    BLUESMAN 1/2 ton status

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    I would get the 3.73's,with your future plan of installing an 454 motor,it will tow well.Look for an 12 bolt rear for that 454.I believe someone in the Az. Republic has a set of 3.73 diffs.Mike
     
  9. steve85fla

    steve85fla Registered Member

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    I would say 4:10, if you are towing they will be the best. IMO
     
  10. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    3.73 is GU6
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I agree that 4.10 would be better for towing.
     
  12. FunBlazer

    FunBlazer Registered Member

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    GU2=2.73
    GU4=3.08
    GU6=3.42
    GT4=3.73
    GT5 or GT8=4.10
    G80=Gov-Loc
     
  13. Rolled

    Rolled 1/2 ton status

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    Thanks for all the responses guys.
    373's it is (or 410's) and maybe I'll get lucky and find RPO codes in the glove box while looking at parts trucks /forums/images/icons/grin.gif
     

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