chassis number help needed
 

hi all, i have been to look at a 53 plate subaru impreza and have a question about the chassis number, i have done a hpi check and all come back ok but when i checked the chassis number on the car to the one on the hpi there was 3 Gs on the cars chassis plate where it shows 3 6s on the hpi check, i also checked the log book and mot certificate and they showed the same as the hpi. i checked around the car and it has still got all the chassis plate stickers on the doors and boot lid that match the cars chassis number. has anyone come across this before? and is there any stamped chassis number on the car? cheers dan.