Complex sentence: Murphy had worked with Seger previously in his very early years prior to his later notoriety, and has worked with Seger on most all studio session work since 1973, and has toured with Seger since 1978.
Split into simpler sentences: Murphy had worked with Seger previously in his very early years prior to his later notoriety. Murphy has worked with Seger on most all studio session work since 1973, and has toured with Seger since 1978.