Easy to find - the back of the card says "Intersection 66, 61, 50 & By-pass 67 and 50." Just keep driving and eventually the street you're on will end up there.

The back: "Dear Fern. Ann Consolozione is going to St. Michaels Hospital today (Sun) I don't know whether you or the Sunshine Chairmen knew about it. Best wishes Henrietta"

That was 1967. We don't know if Ann pulled through. I'm also surprised that no one, in 1967, formed a rock band called the Sunshine Chairmen.