There's a second example, but it was over a century ago. James Clark McReynolds was Woodrow Wilson's loyal Attorney General and a proud lifelong RAT. Wilson appointed him to SCOTUS with the expectation that McRenynolds would be a good reliable "progressive" DemonRat and vote on all kinds of liberal feel-good federal goodies. Instead, McReynolds morphed into a staunch conservative limited government advocate and became one of the most outspoken opponents of New Deal legislation during FDR's regime. His refusal to budge is one of the reasons FDR desperately tried to pull off his court-packing scheme.
One of the reasons there's so few examples of RAT SCOTUS appointees going rogue is that very few RATs actually got appointed in recent decades. Ike, Nixon, Ford, Reagan, the two Bush's, and Trump got to appoints tons of "Republican" judges. RATs like Jimmy Carter got to appoint zilch, while Obama and Clinton got only 2 each.
Stevens was the clown who wanted to repeal the Second Amendment, correct?
I can’t imagine a modern RAT Scotus pick going “rouge” like one of ours can.