erselt,
Many early books thought the GT/CS had sequential lights because it was modeled after the Shelby, but the wiring harness is unique and did NOT have sequenced lights. As for the hubcaps, these are standard options like on all other Mustangs. If you purchased the GT option (along with the CS option) you had GT hubcaps, but if you bought the styled wheels without the GT option, then the plain hubcaps are used. I think this was a reference to say the a GT/CS was not a GT when purchased with just the CS option. And for the 5000 made, that was the original goal for the sale of the CS, however that goal was not being met that is why the CS was sold outside the LA/San Jose sales districts and also how the HCS was designed for Denver.
I would not say the books are wrong, they where probably correct for the time of print but we know through the help of Paul what the real answers are today.
Doug