Up for Buy-It-Now is a rebuilt master brake cylinder, Acme part number 1507.  This item was obtained from an old service garage and is not a newly remanufactured part.  According to my Acme manual, this is used on the following models and years:

1971 Cadillac...All models w/ split system disc brakes

    The master cylinder is in good to excellent rebuilt condition and is free of any damage.  There is a spot or two of very minor surface rust from many years of shelf storage.  May or may not need a light polishing up before installation.  Cast on the piece is 29881.  The original Acme box is in fair condition.
  Please feel free to E-mail me questions.  International bidders are always welcome.  Thanks for looking!!!