I also thought it aired Sunday nights, and doing a quick internet research it did say that it was, indeed, on Sunday nights between The Wonderful World of Disney and Bonanza, NBC hoping those two hit shows would garner bigger ratings for it. I remember Sunday nights as a kid, because it was always agony choosing between Disney and Lassie which aired opposite each other. I'd turn the knob (remember when TV's had knobs?) between the two until deciding which one would take my interest. If my brother was involved and he wanted to watch one and I the other we'd start pounding the you-know-what out of each other until our mother broke it up and wouldn't let us watch anything.
Gerard