3. This act shall not apply to a driver or passenger of:
a. A passenger automobile manufactured before July 1, 1966;
b. A passenger automobile in which the driver or passenger possesses a written verification from a licensed physician that the driver or passenger is unable to wear a safety seat belt system for physical or medical reasons;
c. A passenger automobile which is not required to be equipped with a safety seat belt system under federal law;
d. A passenger automobile operated by a rural letter carrier of the United States Postal Service while performing the duties of a rural letter carrier; or
e. A passenger automobile which was originally constructed with fewer safety seat belt systems than are necessary to allow the passenger to be buckled.