2UW might be another contender, with 69 years of history thrown away as it converted to Mix 106.5.
Now I’m aware that both 101.7 and 106.5 were brought by ARN (from Wesgo and the Albert Family respectively) not long after their conversions to FM, which likely would’ve resulted in major changes for one station regardless. But one still wonders how a “Classic Hits 2UW 106.5” might’ve performed in the ratings against 2WS-FM 101.7 and their “Best Songs of All Time” format…