I played the banjo and harmonica and sang--we were actually a vocal group. I mean, we all played instruments, but we did four-part harmonies, so the vocals were a big part of it. We had two albums on Warner Bros. and some singles on Dunhill. And then we did a single for Phil Spector called "This Could Be The Night" which was--still is--Rodney Bingenheimer's theme song. That's me singing. Apparently, it's one of Brian Wilson's favorite songs, mostly because it's a Spector thing. Actually, Harry Nilsson wrote it, but Phil Spector produced it and recorded us singing it.
-- Henry Diltz 
-  Source: Rhino Records Interview