318 police?how can I tell

If you truly want to know,you need to decode the motor by listing casting number,serial number and production date and the assembly info from the deck surface on the motor to see if its a true cop motor,as the info about the assembly of the motor is stamped in code on the front of the block on the drivers side.With this info we can go from there to see want you have and want can be put in and what needs to be bought new,mrmopartech