American Standard Version (ASV):
These were the sons of Levi after their fathers’ houses, even the heads of the fathers’ [houses] of those of them that were counted, in the number of names by their polls, who did the work for the service of the house of Jehovah, from twenty years old and upward.
King James Version (KJV):
These [were] the sons of Levi after the house of their fathers; [even] the chief of the fathers, as they were counted by number of names by their polls, that did the work for the service of the house of the LORD, from the age of twenty years and upward.