Base - 4cyl, 6cyl, 8cyl (E-tec , LY7, LS3)
LT - Convenience Package on base cars
RS - Luxury/Appearance option for V6, V8 (CTS motor in V6)
SS - V8, upgrade suspension (CTS-V motor)
Z28 - Big Dog - V8, Nurburgring Suspension (CTS-V motor, stiff suspension)(69 Z28 was built for track)
1LE/B4C - Wolf in sheeps clothing/cop car (Z28 that looks like Base model)
ZL1 - Limited Production Top Dog (LS* 427 engine, better build only 69 of them in case they don't sell well.
)
This is just my wish list, directions they could go with the car.