I set this display up (see pictures below) so you can see the difference between the different style Pivot Shafts.

The different styles that I know about can be differentiated by the basic differences in the pivot shaft:

           One style had a bushing that screwed onto the pivot shaft.
                   The set on the left in the picture above (see the detail pictures below First row of the pivot arms)
                   So far as I know these arms were only in early A-Body Buicks 1964 thru 1965.

           There was the Moog replacement Kit K-5250. This is the next set in from the left. It came with two bushings,
                    two bushing retaining washers, two nuts, and one shaft. It currently sells new for about $45.00.

           One style had a bushing retaining Nut. This is the next set in from the left.
                    So far as I know these arms were only in A-Bodies 1969 thru 1972 (have seen these in earlier years).

           One style had a bushing retaining Bolt (it appears there two different style shafts that had the bolt).
                    So far as I know these arms were only in A-Bodies (second set in from the right) 1968 thru 1972.
                    So far as I know these arms were only in A-Bodies (first set in from the right) 1964 thru 1967.         

Any of these pictures can be clicked to enlarge. They appear in the order discussed above.