Complex sentence: Gilbert had fronted several bands and was the lead singer for Ted Nugent and The Amboy Dukes in 1971, touring with them for a year and a half before forming Shadow which led to a record deal with RSO.
Split into simpler sentences: Gilbert had fronted several bands and was the lead singer for Ted Nugent and The Amboy Dukes in 1971, touring with them for a year and a half. Gilbert then formed Shadow which led to a record deal with RSO.