This can be a tricky part if you are just purchasing one side.  Each bar is usually stamped with a RH or LH.  Early Interceptors (and I'm not sure where the break is here) the LH is for the left-hand side of the car. Now some  cars have a top mounted sway bar and the LH link would be used on the right-hand side of the car.   I believe this top mounting sway bar started after vin# prefix 136 but for sure on the late 74's and later.  If you are buying both sides, not to worry.  Not for the usual fretful Mk1s.