If you look around the 1955 and 1956 letters, He is talking about the Stooges and Ted Healy some. He knew the Howard brothers for sure and even sent Betty Healy a press clipping of Shemp's death, stating how he saw Shemp nine months before and he looked great. Also mentioned seeing Moe and Larry on a TV show, but he admits he couldn't remember Larry's name! Only knew him as "the half bald guy" with straight hair, or something like that.
It's strange to think today, but it really makes you wonder how many performers of Stan's generation thought higher of or were more aware of Ted Healy than The Three Stooges. After all, Healy was a highly paid Vaudeville headliner who had a contract with MGM while The Three Stooges "only" made short films for Columbia.