To be certain, you should:
1. Consult your vehicle's repair manual: This is the most accurate way to find the location. A shop manual, a Haynes manual, or a Chilton manual will have diagrams and detailed instructions.
2. Use a reliable online parts diagram: Many websites (like AutoZone, Advance Auto Parts, etc.) allow you to select your vehicle's year, make, model, and engine, then view a parts diagram showing the location of various components, including the EGR vacuum solenoid.
Searching online for "2007 Chrysler 300 EGR vacuum solenoid location [your engine size]" will also yield helpful results, potentially including images from other owners who have worked on their vehicles. Remember to always double-check against your own vehicle.