[COPO]

On the LA car, the C366 has no useful meaning, it does not denote any options and is thought to be a code tied into the week of production.

The potential COPO looks very promising. Another sign would be the Body number from the trim tag being out of sequence with the body number of non-COPO cars built during that time period. I don't have that info in front of me, but one of the CRG guys will probably chime in and give you an idea.