The casting number will give you the cars and dates that block casting was used. Its not very specific, but is always a good starting point. The engine assembly date is the next place to check, which should narrow things down a little.
Block Casting Numbers
The block casting number on smallblock and big block Chevy V-8 motors is located on a ledge found at the rear of the block, most often on the driver's side. This ledge is below the deck of the block and the ledge forms the mating surface between the block and the transmission bellhousing. Some of the later model blocks have the casting number on the passenger side of this ledge. The number itself can have 6, 7 or 8 numeral digits. They might look like this "361959" or "3970010" or "14015445". The block casting numbers do not have any letters in them. There are sometimes individual letters found on blocks like "GM" or "CFD" for the Central Foundry Division, but they are not part of the block casting number. Also some of the later blocks have the size of the motor shown in liters. You may see a "5.0" (305) or "5.7" (350) cast on the rear ledge of a smallblock or a "7.4" on the side of a big block 454. On the side of some later blocks the last three digits of the block casting number are cast into the block, but these are difficult to see when the engine is in a vehicle.
Engine Assembly Date
The engine assembly date is a "stamped in" code that is stamped into the metal as opposed to a "raised" casting. These date codes are can be found in a number of locations on the block, but most often are found on a ledge that is visible when the motor is assembled. This ledge is found on the passenger side of the block deck at the front. If your alternator is on the passenger side of the motor, the ledge on the block deck is right below it. You may have to move the alternator to be able to read this engine assembly code. Some blocks have the engine assembly code on a flat portion of the block above the timing cover mating surface on the front of the block.
Engine Assembly Date/Suffix
There is another type of stamping found on some blocks. This is the "CE" code. You might see something like this "CE123456" on the front pad of the block deck on the passenger side. The "CE" which alternatively has been known to stand for "Chevrolet Engine" or "Crate Engine" was used on blocks that were warranty replacement motors. The "CE" prefix was also used on "over the counter" blocks and engines. If a customer had problems with his original motor, while it was under warranty, it was replaced with an engine that was stamped "CE" with a number of numeral digits following it which serialized that particular engine. Likewise if a purchaser bought a new motor from the Chevrolet Parts counter, the front pad on the pasenger side of the block may have been stamped with a "CE" code.