(a) Two or more authorized insurers may jointly issue, and shall be jointly and severally liable on, an underwriters' policy bearing their names. Any one insurer may issue policies in the name of an underwriter's department and the policy must plainly show the true name of the insurer.
(b) Two or more insurers may, with the approval of the director, issue a combination policy which shall contain provisions substantially as follows:
(1) that the insurers executing the policy shall be severally liable for the full amount of loss or damage, according to the terms of the policy, or for specified percentages or amounts thereof, aggregating the full amount of insurance under the policy; and
(2) that service of process, or of notice or proof of loss required by the policy, upon any of the insurers executing the policy, constitutes service upon all the insurers.
(c) This section does not apply to cosurety obligations.