He did a year for contempt of court.
Castellano also did 5-6 months in 1934 at age 19. He and two friends held up a clothing store in Connecticut and got away with $51. A passer-by happened to see Castellano pulling a gun out of his glove box and reported the license plate to authorities. He was promptly picked up and arrested once he returned to New York.
Never knew about it until I started reading "Boss of Bosses" recently. It's a book about Castellano that was written by FBI agents Joe O'Brien and Andy Kurins, who were part of the FBI's Gambino Squad in the 1980's.
