You will need the upper control arms, as already pointed out, because of the larger ball joint. I'm not sure what size drums the '68's had, I know that a lot of the 9" drum cars were equipped with smaller lower ball joints as well. If thats the case, you'll also need the later lower ball joints and the bolts to go with them. The geometry was the same, so the lowers will just bolt up to the tie rods, but the later model one's had larger ball joints and used 1/2" instead of 7/16" bolts.