INCREDIBLE HULK (1968) #391
War and Peace 2 of 3. "X-Calation." Guest-Starring X-Factor (Havok, Polaris, Strong Guy, Wolfsbane, Quicksilver, and Madrox) Story by Peter David. Art by Dale Keown and Mark Farmer. Rick informs the Hulk that he may be fighting on the wrong side when he discovers the hardware used by the "bad guys" is supplied by the U.S. government. Meanwhile, X-Factor arrives on the scene and things escalate into good old fashioned super-hero fisticuffs. 32 pages. Cover price $1.25.