On a 2004 GMC truck (assuming a full-size model like a Sierra or Yukon), the starter is typically located on the
passenger side of the engine, towards the
bottom. It's usually somewhat difficult to access, often requiring the removal of some components like the engine's lower cover or parts of the exhaust system to reach it properly.
However, the exact location can vary slightly depending on the specific engine (e.g., 4.3L, 4.8L, 5.3L, 6.0L, etc.) and transmission. A repair manual specific to your truck's year, make, model, and engine will give you the most precise location and instructions. You can find these manuals online or at auto parts stores.
