What source would that be and how long ago? Initially Trump stated that he would like for Cruz to be his VP and then Cruz jumped ahead of him in Iowa and Trump went ballistic on him with the whole birther issue, then Cruz won a couple of other states and Trump made up lies about Cruz, his wife and his father. Carson put him on his short VP list and Trump has fired him since. It's hard to believe anything Trump suggests because he's likely to change his suggestion the very next day, or God forbid the MSM might be accused of misconstruing what he actually did say.
The likelihood that Trump will pick Cruz as his VP, is about as likely as him picking Oprah as his VP
He throws these things out there, to see what drama he can muster...and if it's not enough attention, he changes his stance.