The Adventures of Superman, Vol. 1 #449 (1988)

Invasion - The Search
Superman is still missing after he fought the Thanagarians and took a dive. Guardian is out searching, and instead he finds Gangbuster, an unknown vigilante who employs somewhat more controversial tactics and is wanted by the police. The two of them get into an argument about idealism which quickly escalates into physical combat.
Release Date: 1988