I don't often get to clarify a JohnZ post.
Headrests on early 69 cars were optional (RPO A82), but the factory included them on all cars unless they were deleted on the order via RPO AR1.
There were some people who didn't want this mandatory option and the dealership was authorized to remove the headrests, install a plug, and credit them the $16.90.
I won't even get into the screwy price change that happen on 1/1/69.....