To locate them with certainty, you should:
* Consult a repair manual: A Haynes or Chilton repair manual specific to your 2000 Chevy Silverado will have diagrams showing the exact location and routing of the transmission cooler lines. This is the most reliable method.
* Look carefully near the radiator: Start by examining the area around the radiator's top and bottom. Look for metal lines that connect to the transmission and the radiator. Follow the lines to be sure they connect to the transmission.
* Follow the transmission lines: If you can locate the transmission itself, follow the lines that emanate from it.
Safety Note: When working near the transmission cooler lines, be aware that the transmission fluid is hot when the engine has been running. Allow it to cool completely before working on them to avoid burns.