Where is the body control module on 1999 Chrysler 300 m?

The 1999 Chrysler 300M doesn't have a single "body control module" in the same way some later vehicles do. Instead, its functions are distributed among several modules. There isn't one central location. You'll find various control modules throughout the car, including under the dash, in the rear cargo area, and possibly in the engine compartment. To find specific modules related to body functions (like lighting, locks, etc.), you'll need a wiring diagram for your specific vehicle. A repair manual or online resources specific to the 1999 Chrysler 300M will be necessary to locate these.