[70rs/ss]

I believe the upper and lower arms are the same, but ball joints etc are different, If buying new stuff use the 67 arms (or the 72's if they are better) and buy the new parts for a 72 w/discs. I think the mounting tabs for the brake lines are welded to the crossmember, so cut them off and tack weld them to the 67 crossmember. On a scale of what is best vs easiest, swapping the 72 cradle (crossmember and all the related stuff) would be better, maybe even easier in the long run but kinda labor intensive! Jack up the 72 and cut the bolts that hold the crossmember off then roll it out and repeat on the 67, use new grade 8 bolts to put it under the 67 then rebuild as needed.