Where can I find an old version of dropbox app? I'm using Android 2.3 and uninstalled dropbox. Then I wanted it back, but dropbox 3.01, the only official version available, is meant to work only from Android 4 on. Where can I find an old, trustable version of the dropbox 2.x that works for my phone?
Currently the most trustable source for older APK versions is APK Mirror. For Dropbox specifically you can find older 2.x versions here:

http://www.apkmirror.com/uploads/?app=dropbox