Complex sentence: In 1952, they were converted to prototype 25 kV AC overhead EMUs (Class AM1) and ran on the Lancaster-Morecambe-Heysham line until 1966.
Split into simpler sentences: In 1952, they were converted as prototype 25 kV AC overhead EMUs (Class AM1). These units survived in use on the Lancaster-Morecambe-Heysham line until 1966.