if you look at the backcover, then look at the apple logo, and the text in the buttom, if it is the same silver then it is an 3gs, is the text grey, then it is only a 3G
You can also open the handset, and check the dock connector, if it only has 1 connector to the PCB, then it is a 3g, or if it has 2, then it a 3gs
BR
