'74 drive train setup

Discussion in 'GM Powertrain' started by tauchen67, Mar 8, 2010.

  1. tauchen67

    tauchen67 New Member

    just bought a '74 k20 Suburban. It has in it now a 350 motor, 350 auto trans, and 205 transfer case. We plan to use this for going up in the snow, towing (seadoos, 27' boat), weekend road trips, and the occasional trail ridding. The engine runs really high when doing highway speeds. What is the best solution to get the rpm's down at highway? I saw these guys http://www.gearvendors.com/index.html do overdrives, but they are expensive. im sure i can get a rebuilt tranny that will have and overdrive for a lot less than $3000(what they want for an overdrive). But i dont know what model tranny would be best, oh i also have a 454 out of a '77 C30 that i would like to put in eventually and if im pulling the tranny out no time like the present. Any thoughts would be appreciate
    oh currently running 33's would like to go 35's eventually, dont know what my gearing ratio is
    Last edited: Mar 8, 2010
  2. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    If you keep the small-block motor, I'd find a TH700R4 transmission to replace your TH350 with. The TH350 is a 3-speed transmission, the 700R4 is a 4-speed, the 4th gear being an overdrive. That should get your crusing RPMs down. Should be a pretty easy transmission to find, but make sure you get a 4x4 one because the 2wd and 4wd tailshafts are different.

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