* Vehicle Identification Number (VIN): The VIN, located on the dashboard and the driver's side doorjamb, contains a code that indicates the engine. Decoding this code requires a Pontiac VIN decoder (many are available online), but this is the *most definitive* method.
* Engine Casting Number: This number is stamped on a visible part of the engine block itself. You'll need to find the number and cross-reference it with a Pontiac engine casting number database (again, many online resources exist). This requires access to the engine bay.
* Build Sheet (if available): Some owners have original build sheets documenting their car's specifications, including the engine. This is highly desirable but not always available.
* Documentation: Prior service records or sale documentation might specify the engine type.
* Visual Inspection (Least Reliable): While you can get some clues from visually inspecting the engine bay (looking at the size, intake manifold, valve covers, etc.), this is the least reliable method. There's potential for engine swaps, modifications, and misidentification.
In short, start with the VIN. If that's unavailable or indecipherable, the engine casting number is your next best bet. Visual inspection should only be used as a very rough estimate, if at all.
