Where can you find gutar solos on brutal legends

They are on special "Tab Slabs", purple glowing rock items sticking out of the ground. These slabs are all over the map, especially in front of the Cleave (that thing that looks like an anvil), where there are two: Rally Army and Recall Flag. Press Y to read them (if you have it on 360 like me, PS3 players are screwed as far as what I know).