All engines are stamped with an engine ID code, consisting of assembly plant code, production date and suffix code. V8 codes are stamped on a pad just forward of the right side (passenger) cylinder head. 6 cylinder engines are stamped on the passenger side of the block behind the distributor. The block casting number on small block and big block Chevy V-8 engine's are located on the ledge found at the rear of the block, most often on the driver's side. This ledge forms the mating surface between the block and the transmission bell housing. These particular codes designate the specific powerplant that was installed in the vehicle at the factory. Note, this is a general reference.

Code	Power plant	Equipment
CCM	250-155 HP	Powerglide Automatic
CCK	250-155 HP	Turbohydramatic Automatic
CCL	250-155 HP	3 Speed Manual Transmission
CNC	307-200 HP	3 or 4 Speed Manual Transmission
CND	307-200 HP	4-Speed Manual Transmission
CNE	307-200 HP	Powerglide Automatic
CNF	307-200 HP	350 Turbohydramatic Automatic
CNI	350-250 HP	3 or 4 Speed Manual Transmission
CNN	350-250 HP	350 Turbohydramatic Automatic
CNM	350-250 HP	Powerglide Automatic
CNJ	350-300 HP	3 or 4 Speed Manual Transmission
CNK	350-300 HP	Powerglide Automatic
CRE	350-300 HP	350 Turbohydramatic Automatic
CTX	396-350 HP	Manual Transmission
CTZ	396-350 HP	Manual Transmission & Heavy Duty Clutch
CTW	396-350 HP	Turbohydramatic Automatic
CKO	396-375 HP	Manual Transmission
CKQ	396-375 HP	Manual Transmission & Heavy Duty Clutch
CTY	396-375 HP	Turbohydramatic Automatic
CKT	396-375 HP	Aluminum Cylinder Heads & Manual Transmission
CKU	396-375 HP	Aluminum Cylinder Heads & Heavy Duty Clutch
CKP	396-375 HP	Aluminum Cylinder Heads & Turbohydramatic
CZX	400-265 HP	Manual Transmission & 2 Barrel Carburetor sm Block
CRH	400-265 HP	350 Turbohydramatic Automatic & 2 Barrel Carburetor sm Block
CKR	400-330 HP	Manual Transmission
CKS	400-330 HP	Manual Transmission & Heavy Duty Clutch
CKN	402-330 HP	400 Turbohydramatic Automatic Non SS
CKR	402-330 HP	Manual Transmission Non SS
CKS	402-330 HP	Manual Transmission Non SS
CTW	402-350 HP	400 Turbohydramatic
CTX	402-350 HP	3 or 4 Speed Manual Transmission
CTZ	402-350 HP	3 or 4 Speed Manual Transmission
CKO	402-375 HP	4 Speed Manual Transmission
CKP	402-375 HP	400 Turbohydramatic (note L89)
CKQ	402-375 HP	3 or 4 Speed Manual Transmission
CKT	402-375 HP	3 or 4 Speed Manual Transmission (note L89)
CKU	402-375 HP	3 or 4 Speed Manual Transmission (note L89)
CTY	402-375 HP	400 Turbohydramatic
CRN or CRT	454-390 HP	(360 HP) Manual Transmission
CRQ	454-390 HP	(360 HP) 400 Turbohydramatic Automatic
CRV	454-450 HP	Manual Transmission
CRR	454-450 HP	400 Turbohydramatic Automatic
CRS	454-450 HP	Turbohydramatic & Aluminum Cylinder Heads