Where do you guys get this "stuff"???
The engine "code" is a two-digit stamping on the front, near the partial VIN. A '68 GTO 350HP 400, manual trans, would have a "WT" code. A 360 HP version would be WS. The "Ram Air" stuff for '68 is very rare. The auto trans versions usually use a "Y" instead of "W". There ARE variations, but these are the "common" ones.
At the back by the distributor, is the DATE CODE. A 4-digit "tag" (looks like a tag, "cast in"). The first digit is the month (A - Jan, B = Feb, etc.). The second and third digits are the day of the month. The last digit is the last number of the year of production. By using the production code, date code and casting number (7 or 8 digit num ber, cast into the bellhousing flange), one can deduce exactly what the engine is from. Pontiacs with a date code after Jul 7 are generally "next year's model".
A website with very complete Pontiac production data is: