Bob,
Your looking in the right place. Only cars built in Norwood Ohio after the start of the year 1969 used the X code system. That might be 10B (second week of the 10th month (Oct) build). Take some time reading all the sections on the home page. all this is much better explained there. Almost all of your questions can be answered there, and then some. Z/28's have been faked for decades... watch out. good luck. CAMARO CAMARO CAMARO Theres no E in Camaro.
Victor