Only Plymouth for '68.
Service Manuals – MyMopar
Bishko has CD
1968 DODGE CHARGER, CORONET & DART Body, Chassis & Electrical Service Manual CD [eb2621N]
Bishko Automobile Liturature available for 1968, Dodge, Shop Manual
Hamtramck Historical has many Service Bulletins which supplement and correct the shop manual and parts book.
The 1970 Hamtramck Registry Library Page (1965 - 1969)