How to tell 2nd generation from 3rd generation

I have a question that I have been having trouble with. I have a 32 gb iPod touch that i cracked the screen of, and i have since removed the broken screen and thrown it away. Ive read online that for the 3rd generation iPod touch 32 gb you can't use a 2g digitizer and vise versa. the problem is since there is no digitizer on the iPod i can't go into the settings and see if its a 2nd gen or a 3rd gen. Is there any other possible way to figure out what generation it is without the screen on it. Thanks!