Dwight D. Eisenhower's Presidency between January 20, 1949 until January 20, 1957 in many ways defined the 1950s as a decade.
Dewey probably defeats Truman because of Democratic fatigue. Or else if Truman eekes out a victory in 1948, Bob Taft wins the Republican nomination and runs against Truman in 1952. Dwight Eisenhower's last minute intervention in China ended in an armistice between North China and South China in 1961 (after his presidency). Truman's apathy would leave the GMD exiled in Taiwan. I wonder what would happen to Vice President Charles A. Halleck's political career. IOTL, Eisenhower ran out of his home state of Texas, and with Halleck on the ticket, it eroded Democratic support in the South and the Midwest, while strengthening Democratic support in the Northeast and West Coast. I remember Senator Richard Nixon of California being defeated in an upset in the US Senate Election in California of 1956.