Thursday's MEDICINE BALL CARAVAN on KRVS (11am-noon Central Standard on 88.7FM locally or krvs.org) roars with stuff from Gritz, Legendary Shack Shakers, Kelli Jones & Joel Savoy, X, Frigg A-Go-Go, Swingin' Medallions, Eric Burdon & the Animals, Justin Townes Earle, Flamin' Groovies, Mothers of Invention and Captain Beefheart. Also: a tribute to T. Rex.