So, you have left and right dies? The rod is threaded LH and RH?
OK,
Figure the direction on twist that advances by laying the rod across the palm of our hand, so your fingers wrap in the direction that will advance towards your thumb. If you use the right hand to get this correct, the threads are right handed. If you use your left hand the threads are left handed.
Another way to do the same thing is with a nut on the rod lay the rod across the RIGHT palm with the end and your thumb in the same direction. Turn the nut in the manner your fingers curl around the rod or bolt, so from palm to fingertip direction. If the nut advances to your thumb it is right handed, if the nut advances away from your thumb the threads are left handed.
If this still confuses you look up the "right hand rule" with regards to vector math.
Phil