Thanks for the comments.
I agree about CSNY, the Mamas and Papas, and Eagles.
Another great "harmonies" group was the Association. They did some phenomenal vocals. They also sounded great live. Those were the days when you had to be able to SING. No Autotunes back then. Requiem for the Masses was one of my favorites.
There was one of their songs that had a barbershop quartet break in the middle. I can't remember the name of the song, but when I first got my Dokorder 8140, I plugged my little Shure Unidyne B mic in and tried to do that. Absolutely sounded like RUBBISH!

Maybe if I had a clue of what I was supposed to be singing, it might have worked. Working with that syncing on the 1/4" 4track was a pain.
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It was bugging me, so I spent the past 30 minutes going through all the Association songs before I found it. It was
The Bus Song from the Birthday album.