Jm2converter is a jar tool that can port models from WoD to Wotlk, TBC, and Vanilla.
It was originally made by Koward but is pretty hard to find nowadays. Here are the instructions:
"##Usage (example with Frog.m2) : This is a Java command-line tool.
You may need to install Java : Install Java
And setup paths for your environment : PATH and CLASSPATH
Command line : java -jar jm2converter.jar -in "Frog.m2" -out "FrogConverted.m2" <OPTIONS>
##Usage with whole folders(only in oppahansi's version)
Command line : java -jar jm2converter.jar -in "path/to/inputFolder/" -out "path/to/outputfolder/" <OPTIONS>
The "/" or "" at the end of paths is important. New option is -f for whole folders. Only in oppahansi's version.
Type java -jar jm2converter.jar to get a list of all converting options and two examples 
Beware, when you retroport a model, you always lose some data (the newer client features) and you won't be able to get them back if you up convert it back later.
The Legion support is still changing. The game is still in Beta so the M2 format changes. Right now it should work up to build 20810."
These instructions are also included in the download. Enjoy!
