72 C20 motor and markings dont match VIN

[jkrummel123]

Hi, Im new and happy to have a place where I can get help restoring my 72 chevy C20 fleetside. I just got it and am ready to start. I noticed the vin says its an in line 6 but the fender says 8 350 and the motor is a 350. I know the obvious answer is that some one put the motor in later and changed the fender markings but I was wondering if there was a possibility that it was an option from the factory after the vin was made. I just want to restore it back to orig as best I can.
thanks for any help I can get!!!!!

the vin is CCS242B137397, the option plate says nothing about an 8 cyl.