[PC/SR]

Take it to the CHP and ask them for what they need. I am assuming the blue DMV sticker you mention was probably added by the CHP at some time and will hopefully satisfy them as to the authenticity of the number. Otherwise you have lift the body to get the original number from the frame and show CHP the number. I know it is hard to believe but it is probably easier and quicker to go through the CHP and DMV than AAA because AAA is not set up to deal with the old car registration rules and exceptions.