Gearing Question

Discussion in 'The Garage' started by FLOutlander, Jan 22, 2007.

  1. FLOutlander

    FLOutlander Newbie

    Jan 22, 2007
    Likes Received:
    Tallahassee, FL.
    Hello All,

    I have an '82 Chevy C-10. It came stock with a 305 V-8, TH350, and 10-bolt rear end. The engine has since been replaced with a '75 or '76 350 V-8. It's completely stock, and is aching for a rebuild. The stock TH350 is still in the truck...has been rebuilt twice, and needs it again now. My dad did not take good care of this it's mine.

    Ok, now that you know about the truck, maybe someone can help me out. I plan on swapping the stock TH350 for a TH700R4. I need the OD for increased fuel economy. That's all well and good, but I plan on lifting this truck 3 inches and running 33-inch rubber. Stock size is 225/75R15, so about 28.5 inches. Anyway, I'm trying to figure out what gearing would be good to use with this set up? I'm going to rebuild the engine with the intent of getting slightly more HP and TQ, but the best MPG possible. I have NO idea what the stock gearing is. The RPO code simply says "GQ1", which deciphers to "Rear Axle-Standard Ratio(Non-Posi). So is that 2.73 or 3.08? ANy help would be greatly appritiated. I know this truck isn't 4-wheel drive, but I'm trying to learn all I can.
  2. 1977k5

    1977k5 1 ton status Vendor

    May 26, 2003
    Likes Received:
    Best mileage with a 700R4 and 33's? Probably 3.73's or 4.10's

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