Yeah the strut rods are the bars that connect the lower control arm to the front part of the K frame.
The aftermarket ones with Heim joints move much free'er than the stock setup because the stock ones run through bushings and have to compress the bushings to move. With Heim joints the lower control arm is allowed full freedom of movement without any friction. I hope that makes sense. Since there is no bushing to compress the LCA is not allowed any fore/aft movement. I installed a set of CAP bars with Heim joints on my Cuda a few yrs. back and was amazed at how easy the lower control arm moved up and down afterward. With the spindle removed and stock bushings I could just move the LCA from end to end by hand using a good ammount of force (I had poly bushings in it so it was a little stiffer than stock). After installing the bars with Heim joints I could easily move the LCA through it's complete range of travel with 1 finger.