Uncanny X-Men Vol.1 #99
The new X-Men boldly go where no X-Men have gone before as their battle with the mutant hating Sentinels takes to the edge of space and beyond. But before they can stop the madman Steve Lang, the X-Men will come face-to-face with the last people they expected to see!
Printed: Jun 1976
Writers: Chris Claremont
Art: Dave Cockrum and Frank Chiaramonte
Cover: Dave Cockrum