Plastic! X was a transitional version of Plastic! between the stable Plastic! 2.0 release and the later Plastic: Retrofreedom.
Plastic! Retrofreedom was the final release of Plastic!, and utilized a .pworld file format incompatible with the previous .pgf file format.
TLDR (Plastic Music Tracker)
TLDR is an external music tracker that uses Plastic!'s .ptf format.
TLDR is largely the same as Plastic!'s in-game music editor, but has the ability to export .wav files.
Included are a number of .ptf files created using TLDR from 2005-2008.