Gable spanked Joan Crawford in Forsaking all Others and
in Across the Wide Missouri he spanked Maria Elena Marques.The Joan Crawford spanking was rather off screen but the build up was good.You saw her bent over,another guy hands Gable a hairbrush,but you don't see the hairbrush hitting the target.However,you do hear the whacks and her screaming.The one swat spanking you are thinking of may be "Red Dust"with Jean Harlow.I definitely saw him pat her rear,i am just not certain of the title.
Gordon Macrae spanked June Haver in Look for the Silver Lining and Doris Day in On Moonlight Bay.In Oklahoma he threatened Shirley Jones with a spanking.
If it takes too long for these films to come on T.V.,
they are all available at Amazon.com or the relevant scenes can be obtained from Dan Rivera