I have a 1990 Firebird and before i got it, it had went through an engine swap. To my knowledge, it is now the 350 TPI..and was originally stock the 3.1L. Under the hood the sticker reads 3.1 liter..but by the vin code it was the 305?? yes i have tripled checked and it is listed to have been the 305 before swap. Anybody know the reason for this? Just curious