[kh99]

I don't know if there's an existing mod or not, but you could create a radio button custom profile field with options:

Forum Default
Normal
Yesterday / Today
Detailed

(I copy and pasted the description from the "Datestamp Display Option" vb option.) Then create a plugin using global_setup_complete hook location (other hooks would probably work as well), with this code:

switch ($vbulletin->userinfo['fieldX'])
{
    case 'Normal':
      $vbulletin->options['yestoday'] = 0;
      break;
    case 'Yesterday / Today':
      $vbulletin->options['yestoday'] = 1;
      break;
    case 'Detailed':
      $vbulletin->options['yestoday'] = 2;
      break;
    case 'Forum Default':
    default:
      // Don't change value
      break;       
}

(of course you need to replace the X in the first line with the actual field number you created.)