No, Jimmy Stewart never acted on the Fibber McGee and Molly radio program.
However, as we outlined in our book, he did appear on four different programs to promote his own show, The Six Shooter. That show had recently changed its broadcast day from Sunday to Thursday and these spots were meant to alert listeners to that fact. All four appearances came during the final break for the 15-minute program. One of the programs on which Stewart delivered his message was that of May 5, 1954:
Here’s what he had to say:
