will an iphone 4g /4s case fit a iPhone 3gs (at&t)?

I'm cheap. when i upgraded i got the iPhone 3gs, which works just fine for me, although the new one would have been great.

anyways, I'm shopping on amazon.com and they have some freaking awesome cases, but for the iPhone 4s. I'm actually having a hard time finding anything for the iPhone 3gs. I've read that the iPhone 3gs is a bit larger than the 4s... so i was thinking i could buy one of the rubbery ones and make it stretch? does anyone know about this at all. I'm pretty sure its a given that a hard case won't fit... but id still like confirmation

also, i was thinking about getting a 3gs underwater case, and maybe trying to put the rubbery one over it? ill include links

thanks for ANY INFO!!!!!!

http://www.amazon.com/gp/product/B004VYFTIY/ref=ox_sc_act_title_3?ie=UTF8&m=ASML43TP7P45Y

http://www.amazon.com/gp/product/B00700V0B6/ref=ox_sc_act_title_1?ie=UTF8&m=ASML43TP7P45Y


http://www.amazon.com/gp/product/B006MPPB0Q/ref=ox_sc_act_title_4?ie=UTF8&m=ASML43TP7P45Y

also, if you have any recommendations for a 3gs att case, please let me know with links!! since I'm so cheap.... the cheaper the better!!

thanks again!