Quote Originally Posted by Explicit_Spade View Post
8th digit is the engine code, 4 is Supercharged.
5th digit is the Platform Series code. R is a GTP.

You infact have a GTP from the factory.

Don't believe me? Here's a link so you can figure it out for yourself Vehicle Identification Numbers (VIN codes)/GM/VIN Codes - Wikibooks, open books for an open world
well it must be just the upgraded gtp engine package and base appearance package to save money for the original owner which was the police dept