You know, there are probably four or five scripts here that attempt to number tracks or filenames the way people want. This has been an activity going back to SoundJam. Number Song Names by Play Order approaches the problem a little differently. The script will prefix each selected track's Song Name (I use the old "Song Name" nomenclature when actually the Song Name is now called "Name") with the number of its order in the selection (01, 02, 03...and so on). The selected tracks must be in a playlist that has been sorted by Play Order; ie, a user-created playlist, not a so-called "Master" playlist. The selection of tracks need not be contiguous, however it is important to have already established the Play Order. There's also an option to inhibit iTunes from renaming the tracks' filenames, since iTunes will automatically do that when you change a Song Name.