Hello. I have an iPhone 3gs that works perfectly, but its case has been kinda smashed on the back after an accident. My question is, i can get an old iphone 3g from a friend which is in perfect condition externally. Would it be possible to replace the 3gs' case with the one from the 3g? (i have the tools and i'm comfortable doing it etc etc) Basicly, would the insides of a 3GS fit in a 3G case? Thanks!