The following story appeared in the April 13, 1949, edition of Variety:
The final paragraph is what caught our attention. It seems that to promote the April 16th event a series of 30-second and 1-minute spots were recorded for play on many of the local, Los Angeles area, radio stations. Heard on these spots were Jimmy Stewart, Van Johnson, Ray Milland, George Murphy, Walter Pidgeon and Robert Taylor.
As you may well guess, none of these promos appears to have survived.