To find it, you'll need to:
1. Identify your engine: Check your vehicle's documentation (owner's manual) or the sticker on the driver's side doorjamb to determine the engine type (e.g., 4.7L, 5.7L Hemi, etc.).
2. Consult a repair manual: A repair manual specific to your year and engine will show you the exact location with a diagram. You can find these online (often as downloadable PDFs) or at auto parts stores.
3. Search online forums: Search online forums specific to Dodge Ram 1500s (like RamForum.com or similar) for your specific year and engine. Many owners have posted pictures and descriptions of their fuel filter locations.
General possibilities (but NOT guaranteed for your specific truck):
Many 2006 Dodge Ram 1500s have the fuel filter located within the fuel tank itself, meaning it's not easily accessible without specialized tools and possibly dropping the tank. Others may have it in the fuel line, somewhere under the vehicle. Again, consult a repair manual or online resources specific to your engine.