I have installed them incorrectly in the past . Even though I knew better but was in a hurry and just plain forgot. They did not break but one adjuster was in much more than the other to get the ride height correct and level. Which is how I realized my mistake. Not too hard to correct...
On the torsion bar, the hexes at each end are not in line. Thus each side is different. Lay the bar on a flat surface and you can see it.
I ran into this question some years ago and did not get a clear answer as to what direction or side . I don't know everthing but I view a torsion bars function the same way an extention bar on a socket set function and is used to absorb and transfer forces so why would it break when twisted either way ??? I have removed and reinstalled them and if my momory is correct I ended up with two r marked torsion bars and installed them as I had no other option and I have not spotted a difference. That car was sold so I don't know if they had a problem but the car ran and sat well.
When I got my rolling-shell Dart, it had .89 t-bars... I discovered when removing them (to install headers on the big-block) that they were both R. The car had been working fine at that point and the ride height was settable. While they were out, though, I got (newer, clocked) PST 1.03 bars and greatly improved the ride. And made sure to put them in L & R
