73-86 dropped spindle question

[vics stuff]

My truck is a 1972 . And you are correct on matching the ball joints to the spindles. I would tend to believe that this company sold a drop spindle for 1983 - 1987 ?? and said these are what is being used on the 1972 pickups. What I do not understand is , that they do not indicate to use lower control arms off the same 1983 - 1987 on the installation instructions. A bit strange. I hope I do not end up with major issues on the installation.
Will keep you informed