http://www.pontiacpower.net/castnum01.html

go to this link as well and it will tell you everythig you need to know and where to find it. Sometimes the engine code and even the casting number will not tell you what you need as there are some casting numbers and and leters that hve been used for multiple years. I had to remove an exhaust manifold recently to determine an engine I had sitting around to find the displacement stamp only to find it was a 350 when other indications pointed to a 400.