Cal. Health and Safety Code - HSC § 18040. Section 18040.
(a)
With respect to the sale of any manufactured home, mobilehome, or commercial coach that has not been previously installed on a foundation system pursuant to Section 18551, a dealer may solicit or obtain listings, engage in the multiple listing only with other dealers, or engage in payments only to other dealers or groups of dealers, pursuant to cooperative brokering and referral arrangements or agreements on the sale of only a manufactured home, mobilehome, or commercial coach which has been titled by the department.
(b)
With respect to the resale of any manufactured home or mobilehome that has not been previously installed on a foundation system pursuant to subdivision (a) of Section 18551, a dealer may solicit or obtain listings, engage in multiple listing, or engage in payments with other dealers, groups of dealers, or with real estate licensees licensed pursuant to Chapter 3 (commencing with Section 10130) of Part 1 of Division 4 of the Business and Professions Code.