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  1. #1

    Default '74 drive train setup

    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 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 by tauchen67; 03-08-2010 at 08:28 PM.

  2. #2


    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.

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 277K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half

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