Just think of it: Bob Dylan and his band pounding out a furious version of “Pump It Up.” Or Elvis Costello, solo on guitar, rattling off a spot-on “Subterranean Homesick Blues.” Perhaps the two of them could cover each other’s “I Want You.” Imagine the possibilities as two of music’s most influential singer/songwriters team up for a fall trek. Click here for a complete list of dates.