In general, the taller nut is for the differential attachment, through 1970, and the shorter nut is for the axle flange. There were several variations between 1957 and 1974, and substitutions could happen. Both areas use 9/16" hex nuts with 3/8"-24 threads. The following image shows both common nuts:
View attachment 154496
The taller nut, part number 6027412, was used from 1968 into 1971, and the height specification is 0.4 inch. Actual height can vary some depending on wear and original supplier variance. The following image shows a height measurement on the taller nut:
View attachment 154498
A similar nut, part number 1485066 was used 1964 - 1967, and
The shorter nut, part number 6026131, used in 1970 - 1971 and some earlier, was installed on nine of the axle flange mounting studs. A similar nut, part number 6028915, was used in 1972 - 1974 as an alternative to 6026131. The following image shows a height measurement on the shorter nut:
View attachment 154497
The shorter nut, part number 6028915, was also used as a differential mounting nut starting in 1971.
The nut on the passenger side axle flange adjuster retainer is a different lock nut, part number 2404168, used 1965 - 1974. The following images shows the 2404168 flanged nut, next to another locking nut, part number 1927232:
View attachment 154499
The flanged lock nut has a height of 0.41 inch.
The other lock nut, 1927232, was used previously in 1965 - 1968 as an axle flange nut instead of 6026131, has a height of 0.32 inch. Prior to 1965, the tapered axle flange nuts were part number 120369.
