Sherman Minton probably replaces Douglas. He was one of the top three choices for Black's seat along with Stanley Reed and Black; plus he was a Circuit Court judge by this point and Black lobbied to get him on the bench.
Given how close Black and Douglas were, Douglas probably promotes Black to Chief when Stone dies in 1945. If that happens, Jackson very likely retires out of frustration.
Fred Vinson and Tom Clark were friends of Truman, so I doubt Douglas puts them up. And even if Douglas wants to put a Republican on to replace Owen Roberts as a bipartisan gesture the way Truman did, it'd probably be somebody more liberal than OTL's Burton.
Herbert F Goodrich of the Third Circuit and Dean of University of Pennsylvania Law School was considered at one point.
Arthur T Vanderbilt, Chief Justice of the New Jersey Supreme Court, President of the American Bar Association from 1937–38, and Dean of New York University Law School twice declined offers to be on the United States Supreme Court. He was also a Republican.
Erwin Griswold wasn't Dean of Harvard Law School until 1946, but he was already a somewhat prominent lawyer working for the Government, developed the bluebook system of legal citation (which is still used today), and in 1942 co-authored a piece in the New York Times supporting Black's dissent in Betts v. Brady with New Deal lawyer Benjamin V. Cohen. He was also a Republican.
Abe Fortas was a student of Douglas's at Yale Law School and impressed Douglas enough that Douglas got him a job at the Law School. By 1945 he'd had a whole range of government positions.
Thomas Dewey might be nominated just to keep him from running for President against Douglas in 1948. Eisenhower and Nixon offered him the Chief Justice spot, but he said no both times. He didn't want to give up all of the money he was making in private practice. He'd be liberal on racial issues but conservative on criminal procedure.