To find subtitles specifically synced for the release, you can check major subtitle repositories that index files by their scene release names.
Since this is an older XviD release, the timing is specific to the frame rate and cuts of that particular "DiAMOND" encode. You can typically find these files on: subtitle Idiocracy.LIMITED.DVDRip.XviD-DiAMOND
Look for entries that mention "DVDRip" or "XviD" in the description, as these are most likely to be compatible with your version. To find subtitles specifically synced for the release,