Milacron stamp and strange number  

Hi,
I just went into a strange chair... it has no embossed logo inscription at all but just a stamped C star (milacron logo) in black ink in a rectangle with a number that is definitly not a date.
the only other thing on the chair is a perfect condition patent paper.. with only a few patents... 3 starting 147 and two 150 .. so 5 lines only... no red date on the patent paper..
it is Elephant hide gray in color and shockmount seems to have been changed from large to small.
can someone tell me more about the date and origin of this chair?
I am not sure if I'm going to buy it or not...
🙂
thanks in advance and congratulation for the great info on the forum