Gary Bell, a top post-production exec for MGM during a career that lasted 50 years, died of natural causes on his boat in Marina Del Rey, Calif., on Sept. 21. He was 71.Bell started in the MGM mailroom in 1963. After a year he moved to the lab, then entered the cutting room in 1966, starting on “Grand Prix” and working on more than 20 films. He was named director of post-production for MGM in 1977 and then was promoted to senior VP of post-production of MGM/United Artists. In 1991 he started consulting, working with Universal, MCA Recreation, SDDS and Cinecolor-Bangkok in Thailand. Bell also served on various committees for the Academy of Motion Pictures Arts & Sciences. He is survived by a daughter; two sons; five grandchildren; his brother; four nephews; and two nieces. A memorial service will be held on Thursday, Oct. 11, at 11 a.m. at Holy Cross Mortuary Chapel, 5835 W. Slauson Ave., Culver City.