Here's the history of the Chrysler 7 1/4 pinion seal part number. For those of you familiar with the Chrysler parts catalog, its found under 3-22-45.
1960 thru 1965 part number - 2070113
1966 thru 1968 part number - 2404134
In 1969 Chrysler superseded 2404134 back to 2070113
It may seem strange but sometimes Chrysler would supersede a newer number back to a older one.