Not sure if there are different sizes or not, but dad n I had problems with his bushings for 67 cuda. On his there was a wavy/spring washer missing...got it installed and had to tweak it a bit, but works good now.
The ones with the spring washer are a little different than some of the others.
On my 73 Swinger they were all the same size there were no other pieces at all other than the plastic cups in the arms.