1957 Buick Special 46R Positraction ?

Discussion in 'High Tech for Old Iron' started by gooch, Jun 13, 2018.

  1. gooch

    gooch Member

    I want to apologize ahead of time if this question has already been asked but I'm currently rebuilding a '57 Special with a manual trans and mating it to a '66 425 (old 364 block cracked) and to help it hook up I'd like to know if there is a bolt in "positraction" rear differential that would work.

    In some of the early Chevy's I know that they were easily identifiable with the large "P" cast into it. Are these interchangable or is there another option

    Any help would be appreciated.
  2. 56buickboy

    56buickboy Well-Known Member

    Gooch, there was more information here on V8 Buick about early posi diffs but it seems to have been archived somewhere. Is your manual trans still going into torque tube? I'm guessing 57 then yes.

    I do have a 61 - 62 posi with 3.23 gears that was hard to find, nice internally but pinion flange and nut badly pitted from sitting outside somewhere nasty. Parts are extremely hard to find so will go 9 inch for my 425 56 but may use the posi in my sons 40 Ford PU, 322 power.

    These links may get you started and someone with more knowledge may be able to help with finding archived information.



    Just found this thread with links to jalopy journal.......
    Last edited: Nov 5, 2018

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