Thanks guys, I found a link aff of one of those links that got me to here.
Vehicle History Reports - VIN Number Used Car History Records - DMV.ORG
There you can enter a vin and it gives year make model and engine. I double checked it with a VIN of an 07 that I knew had the 5.7L and it is acurate. The truck in the add I was looking at is a 4.7L. I am looking for a 5.7L. Thanks again for the help.