When the Director of Classification and Compensation finds that in a particular geographic area or areas wage practices prevailing among private and other non-State employers for a given occupation would warrant a shift pay differential for employees in the same or related occupations in the State service without, however, any substantiating evidence that such wage practices are prevailing on a Statewide basis, he may, after a hearing which shall afford the employees affected or their representatives an opportunity to appear and be heard, authorize a shift pay differential, subject to the approval of the Director of the Budget, for such same or related occupations in State service in one or more geographic areas which may vary among geographic areas and among work shifts.