Boy O Boy, That it was.
I think 580 was hwy-17 in those days. I still tell people about a sign that was once at the hwy-17 and 101 interchange. The sign looked like a bowl of spaghetti and said 'MINGLE', no kidding.
My only child (Dr blam) was born in San Jose hospital in 1968. He presently lives in Glendora.
As I remember, Hwy 17 was the 'Bloody Nimitz.' The 580 a.k.a McArthur, runs to the east, roughly connecting Hayward and Oakland via pretty green rolling hills. The Angels on their bikes and in their 'colors' seemed jarringly out of place in that upscale environment. I guess their 'business' interests enabled them to buy real estate wherever they wanted to. As for the sign at the Nimitz and 101, I don't recall it specifically but I certainly came close to "mingling" on it any number of times. That was (and maybe still is) one scary freeway!