An LDS missionary records in his journal Harold B. Lee's answer (given in the temple) to the question, "If the "second endowment" existed and "if so, what connection does it have with the Holy Spirit of Promise, and who receives it and why and how," Lee's answer: "You don't have to worry. You've received all the ordinances necessary for exaltation....It is a special blessing given by the President of the Church to men who have been called. It is not necessary to receive it, however. You have all the endowment you need to be exalted."
[On This Day in Mormon History, http://onthisdayinmormonhistory.blogspot.com]