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input and output spine counts for a 350/th350/np203

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by xnoahx, Sep 13, 2002.

  1. xnoahx

    xnoahx 1/2 ton status

    Oct 12, 2000
    Likes Received:
    Ventura, CA 93004
    Ok, Im looking to get an overdrive trans, i found a TCI on here that a user has and I was just wondering about some of the spline counts that concern the trans right now im pretty sure that my th350 has a 27 spline output but im not sure about the input. were there different counts for different years? I would like to get the trans but I dont want to get something that wont fit.
  2. HarryH3

    HarryH3 1 ton status Author

    May 31, 2000
    Likes Received:
    Georgetown, TX
    The input splines on the transmission don't matter. You have to use a 700R4 torque converter anyway, which just bolts to the flexplate. Both the Turbo 350 and the 700R4 have 27 spline output shafts and a square, 4-bolt pattern that the t-case adpater bolts onto. The only thing you have to watch is that there were a few different output shaft lengths. Get the length of the stickout of the output shaft on the 700R4, then compare it to yours. Measure from the back edge of the transmission case, rather the the adapter, to get a true measurement.

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