Notwithstanding the provisions of chapter 67, the Commissioner of Public Safety, consistent with budgetary allotments, may (1) promote two state policemen to the rank of sergeant to serve in the position of commissioner’s aide, and (2) upon the request of the Governor, promote two state policemen to the rank of sergeant to serve in the position of Governor’s chauffeur-bodyguard. Such policemen appointed to the position of commissioner’s aide shall retain the rank of sergeant after the commissioner’s term of office expires or upon the commissioner’s removal, resignation or failure to complete his term of office until such policemen have the opportunity to qualify at the examination given for the position of sergeant following the conclusion of such assignment. Such policemen appointed to the position of Governor’s chauffeur-bodyguard shall serve at the pleasure of the Governor and shall retain the rank of sergeant upon conclusion of such assignment until such policemen have the opportunity to qualify at the examination given for the position of sergeant following the conclusion of such assignment. In the event any such policeman does not qualify for promotion to the rank of sergeant he shall return to his permanent civil service rank. Any such promotion of any state policeman by the Commissioner of Public Safety or by the Commissioner of State Police prior to November 1, 1990, is validated and such policeman shall retain the rank held during such assignment.