The band's biggest hit was "Got A Line on You"
Cassidy is the bald one. Below is a profile on the drummer.
In the late 60's Led Zeppelin toured with Spirit as an opening band. It has been said Spirit was influential to Zeppelin and Cassidy's drumming was of some influence on John Bonham.
Here is Spirit performing a song live in 1979,,,
Sad news but atleast he Dave Cassidy lived a long life and his music lives on.