Serial numbers have six numbers, with a three digit suffix. The final numbers are the sequential order of the model made during the lifespan of the model (not that year).
When Fender took over production in January 2003 the serial number scheme changed again, and Fender-era serial numbers have a two-character originating factory code, followed by year and month, and finally a sequential ordering number.
Most Electromatic hollowbodies carry a KS designation, although KP was fairly common prior to about 2007.
CY is usually seen on Electromatic solidbodies such as the Corvette/CVT.
On hollowbodies, the label is usually visible through the f-hole.
On other models such as solidbodies, it should be inside a control cavity.