Fidelity Research Cartridges?

I just bought an FR Mc 44 cartridge, and I must say, it sounds really good! It really sings mounted in a FR 64 Fx and a FR headshell.

Unfortunately, there isn`t much information about FR- cartridges at all on the www. Does anybody out there know anything about:
1) When was this cartridge produced?
2) Where does the Mc 44 stand in the FR- hierarchy?

As i wrote, I am really impressed with the sound of this cartridge, and I am a little surprised that there is such scarcity of information about it.