(1) If so authorized by an insurer, the commissioner shall accept, in lieu of filings by the insurer, filings on its behalf made by a rating organization then licensed as provided in this chapter.

(2) As to fire insurance under a standard form fire policy, and the following insurances (other than vehicle insurance coverages) when issued as part of a standard form fire policy, an insurer may so authorize a rating organization to make all [of] its filings only, and may not make a portion of such filings upon its own behalf and authorize a rating organization to make other such filings:

(a) Additional property insurance coverages; or

(b) Coverages including any kind of insurance in addition to fire for a single undivided premium.

(3) Except, that notwithstanding the provisions of subsection (2) an insurer which prior to the first day of January, 1947, made its own filings in this state as to a particular class of fire risks, and its filings in this state as to other classes of fire risks were made by a rating organization authorized by the insurer so to do, may:

(a) Continue to make all [of] its own filings as to such specific class of risks or authorize a rating organization to make its filings as to such specific class of risks or any part thereof; and

(b) Authorize a different rating organization to make all only of its filings [all of its filings only] as to all other classes of risks insured by it in this state against fire under the standard form fire policy; or

(c) Make all [of] its own filings as to all classes of risks insured by it against fire under the standard form fire policy, or make all [of] its own such filings except as to any which may relate to any such specific class of risks, which filings so excepted the insurer may authorize a rating organization to make; or

(d) Authorize a rating organization to make all only of its filings [all of its filings only] as to all classes or risks insured by it against fire in this state under the standard form fire policy.