In the file trackID.gxt2 you can find songs that were supposed to appear on the radio station, but did not make it into the final version of the game:
Bramma Feat. Elephant Man - Duh Weh Mi Waah Dennis Brown Gregory Issacs Junior Murvin - Police And Thieves Lee ''Scratch'' Perry & The Upsetters - Jungle Lion Leo Graham - Want A Wine Linval Thompson - Jah Jah The Conquerer Sean Paul Sizzla - Living Up
These tracks were found in an early PlayStation 3 dev build: Mikey Dread - Dread At The Controls UB40 - Red Red Wine