Quote Originally Posted by Bob Parmenter View Post
Mortec Chevy Smallblock V-8 Casting Numbers List
....which even with one number missing (6) tells you it's a 1968 small block, but it could be machined as a 302, 327 or 350. You need the stamped engine number from the machined pad, either on the passenger front just below the head, often tucked behind the alternator or on the driver's rear, just above the bellhousing. I've seen both locations called out for the SBC's, and I don't know if either is 100%. Should be two stamped numbers, the engine code and a partial VIN.