Vikki, that one will be a bit out of my range. My Feb '85 Toyota MR2 was my last car living in So Cal and it was 1NCN393. I left a year later for my 6 year tour of Europe. So I am not familar with the plates my family had on their later cars. My mom had a '89 Plymouth Acclaim that I could have used to frame your plate with.
So I can kinda guess at late '80's. Let's say 1987. I have a photograph at home of my father outside a famous LA landmark restaurant that dates back to that period. I dated the photo based on the license plates and my father's journal. I will see if I can't dig up the photo over the weekend.
That's the best I can do at the moment. I will ask my brother if he can help. He still lives there.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI