To be certain, you should:
* Consult your owner's manual: This is the best resource for the specific location on your vehicle.
* Look under the vehicle: Use a flashlight and carefully examine the area under the rear passenger side. The canister is usually a cylindrical or rectangular plastic container with hoses attached.
* Use a repair manual or online diagrams: Repair manuals (like Haynes or Chilton) or online resources specific to your year and model Avalanche often include diagrams showing the location of components like the evap canister.
Be careful when looking under the vehicle. Support it properly if you intend to spend time underneath.