Master cylinder question? What's it fit?

Got this master cylinder in a "lot" purchase of some parts, earlier during the year.
But haven't been able to find out the proper application for it.
GOOGLE, or Bendix, Wagner, Raybestos, sites haven't been of any help to me.
Anyone know what casting number, or part number, 29861 may be for?
I'm suspecting it's a manual brake, front drum, rear drum, master cylinder, but not sure, and it's original application.
Anyone know?
Thank's a lot.
hemi71x


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A picture of the piston would help, is the hole deep or shallow, what diam, are the reservoirs the same size?