Anything about Kadett "A's" is real hard to find out about because there are so few of them left out of the 600,000 or so that were made.
Found this site:
OPEL KADETT A (1962-1965) - Bochum, ich komm´ aus dir which has a little bit about them - but it is in German. Fortunately up in the top RH corner is a link to 'Babelfish' that you can click on to have it translated. When 'Babelfish' appears just copy the site address into the box starting with http:// and select translation from German to English from the drop down menu and you will get a quaint translation of the site. Have a wander around the site and some good Kadett A info turns up.
HTH