If with respect to an insurer lawfully authorized to transact insurance in this state immediately prior to the effective date of this section, this title requires a greater amount of capital, surplus or deposit than required of such insurer immediately prior to such effective date, such insurer shall have a period of one year from and after such effective date within which to comply with any such increased requirement. No such increase shall be required of any domestic stock insurer which as of such effective date, was lawfully authorized to transact in this state only automobile physical damage insurance, and for so long as such insurer does not transact any additional insurance.