Need Blueprints for 1985 Nashua-Zimmer Mfg home

[redLisa]

I have a 1985 Nashua-Zimmer Mgf home. In order to get a permit for solar, the Calif Housing Authority wants to see the blueprints or engineering documents. That is what the installer says. It has a 433 permanent foundation but they want the specs. How or where do I find this ? Or do I hire a civil engineer to make these ?
Thank You !