Good find, Karl. Here's a little recap: (pics)
(#1)The first was the Jumbo/ Torpedo Cross Country Bus, 1937 issue, with "TRANSAMERICA" and sometimes "GREYHOUND" on the sides. (#2) A rarely seen two-tone 1941 Greyhound with white wheels and interior front axle support appeared in a set, but not in large numbers. When production resumed after the war, black tires were standard (That's yours). Soon thereafter, about 1948, Tootsie produced (#3) the 6 inch GMC Greyhound.I like them all!