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Replacment for granny 4 speed

Discussion in 'Chevy Trucks' started by ejschwarsjr, Sep 19, 2002.

  1. ejschwarsjr

    ejschwarsjr Junior Member
    from S.Tx
    Messages: 1

    You all have a cool site. While I live in southTx and never see snow, I do two old chevys. One is an 87 C20 hd, and the other is a 85 C30 Parcel van.

    A previous owner of the C30 installed a Cummins 3900T diesel. I like the motor, thou it slow as a snail getting to 55 and tops out at 70. My problem is the muncie 4 speed transmission. I need the granny for pulling but another gear or two on the way to fourth (1:1) would sure help things along. Does any one know if any one made a 5 or 6 spd box with a granny gear.
  2. Rocky383

    Rocky383 Junior Member
    from alaska
    Messages: 12

    there are 5 and 6 speeds with a granny gear and i think they are made by new venture but they are very expensive and i doubt if they are a direct swap. also there are underdrives( i thinks thats what they're called) that you can bolt in to make your 4 speed a 8 speed effectively. i think they just split each gear in to two.
    hope that helps!?!
  3. plowking35

    plowking35 2000 Club Member
    from SE CT
    Messages: 2,923

    The new venture 5 sp should be a direct bolt in as far as engine to tranny, as long as the cummins has the same bell housing pattern as a chevy. If not a dodge 5 sp may work.same tranny different bell housing pattern.
    The cross member may need some mods tho.
  4. Pelican

    Pelican 2000 Club Member
    Messages: 2,075

    The Super Duty Fords have a 6 speed tranny, the shift knob says it's a 5 speed overdrive with a low low. My truck has 4.88s and the low gear is a stump puller, but at 55 mph I'm turning 2200 rpm. It might work better with higher gears, but I don't know how much trouble it would be to adapt to your engine.