Complex sentence: In the 1950s and 1960s some Whiskey submarines were converted to guided missile submarines, with the capability to fire one to four SS-N-3 Shaddock cruise missiles.
Split into simpler sentences: In the 1950s and 1960s some Whiskey submarines were converted to guided missile submarines. These boats had the capability to fire one to four SS-N-3 Shaddock cruise missiles.