Actually, Trump tilted over to the GOP about 12-15 years ago. He's given lopsidedly to GOP candidates and causes, with a few exceptions (mostly in NYC) in the last 10 years or so. Someone posted up the data in another thread.
He used to donate about 6:1 'Rat, 25 years ago, but that's almost reversed the last few years.
FYI.
(Truth in advocacy, I'm a Cruz supporter, but would accept Trump (like a lit road flare) if he won the nom.