 Sarah Smith reporting. So what more do we know about Donald Trump's running mate, 39-year-old J.D. Vance? Well, just two years ago, he described himself as a never-Trumper. And at one point, in a private Facebook message, wondered whether the former president could become America's Hitler. Mr. Vance is a graduate of Yale, a former Marine, and author of a best-selling book turned film called Hillbilly Elegy about his humble upbringing. Republican Congressman Tim Burchett from Tennessee told us more.