1968 johnson 20 long shaft parts fit 1971 short shaft?

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  • April 1, 2017 at 1:42 pm #55296
    outbdnut2
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      US Member
      quote 1946Zephyr:

      I believe that these are ALL interchangeable in the 15, 18, 20 and 25, from 1955 – 1973. 1955 – 1957 10hp, as well. The 5 bolt lower had a common cross over, even though the gear case and cavy plate was different in appearance. Like Mumbles said, just make sure the drive shaft has the 4 splines. Military and commercial models may be like 21 splines on the top of the shaft.

      I agree that Short and long shaft components on these motors that I’ve seen are pretty much interchangable, but since powerhead swaps were mentioned in a couple posts here, to avoid any confusion, I have to say watch out if swapping entire powerheads between models through 1958 with newer ones that have thermostats. The water passages are not the same so powerhead swaps of motors up through 1958 with 1959 and up motors will not work.
      Dave

      April 1, 2017 at 3:14 pm #55308
      1946zephyr
      Participant

        Agreed. I don’t see where I mentioned anything about powerhead swaps, but you are correct.
        Thermostats came in OMC twins, in ’59 and later (except for 28 and 33 hp) and ’58 and later for the Big Twin models.
        Oddly enough, the 28 and 33 were derived from the older Big Twins of 1956 and 1957 with two less horses each.

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