Confused on Spring kit 68 dart

Switchover for the self adjusters was the begining of the 1969 model year. That's for all Chrysler, Plymouth, Dodge. Get the '69 and up shoes, self adjuster & hardware if you go that route.

You can dig through factory tech pamphlets here for pics and tips
http://www.hamtramck-historical.com/MTSC/1969/ServiceConferenceMenu.shtml
and many more
http://www.imperialclub.com/Repair/Lit/Master/index.htm