Very rare, but discs were offered on Cs in 65. Very rare. Marketed to police and trailer tow/fleet use at first IIRC.
I remember we discussed this before, probably on the Dry Dock. At that time I found some info in a 1965 parts book that specifically listed the disc brake setup under special police equipment.
EDIT: I found it. Here is what I wrote. References are to the 1965 Factory Parts Book. I also remember that the 15" wheel covers depicted were not the ones for 66-67 disc-equipped cars which
@Ripinator posted pics of in this thread.
Section 2 does not list the special lower balljoints for disc brake cars.
Section 5 shows exploded diagrams of the disc brake system for C-body Plymouth, Dodge and Chryslers. However, the part of section 5 listing part numbers is missing, so we can't see if the disc specific parts are called out here.
Section 22 lists hub and brake related parts for discs, specifies they are for Polara and Fury and specifically for police vehicles. It also shows only one style of 15" wheel cover, and specifies that it is for police and taxi use.
Looking in the Police and Taxi section, there are disc brake related part numbers shown for Dodge Polara and Plymouth Fury under the police car section, but not under the taxi section.