I’m in Washington so I can’t speak for the laws in Cali. However, I can tell you don’t move a 1970s trailer. There is a year in the 1970s where they still used aluminum wiring. They stopped in the mid 1970s, but I can’t remember if it was 1973 or 1976. Cali has strict laws on things, and I can imagine moving an old trailer with possible aluminum electrical wiring could be a problem. We have a law in WA that states that if you move a certain year in 1970s (I don’t recall if its '76 or older) you have to, once its placed and permitted, bring everything up to standard building code. Which makes resale pretty impossible for a reasonable price for that age home. Food for thought. Your permits office would be able to help you a lot if you call and ask them directly in the city you are looking to move it to. Best of luck.