duplexer HP LJ 4050/4000 printer (West Bradford Twp)

I'm looking for the duplexer module from a Laserjet 4050 or 4000 printer so I can print on both sides of a sheet of paper and be more environmentally correct. I will pick up the whole printer if necessary, as long as it has a working duplexor. If the fuser module is clean and working, I'll also take that.