As noted, the CAP used the first version of the "closed crankcase ventilation" equipment.
In those earlier years, people who towed trailers seemed to be a little more intense in making sure their vehicles were actually capable of hauling a trailer, reliably and safely. This included making sure the better axle ratio was ordered, a heavier transmission, and enough power in the engine. There seemed to be more places that catered to these needs than in more recent history, or they have shifted their focus from cars to light-truck chassis vehicles.
Many things were added "aftermarket", as the auxiliary automatic trans cooler in addition to the one already in the bottom of the radiator tank. If the car was ordered with integral factory a/c (as opposed to the add-on under-dash Mopar a/c unit (or other similar system), it should already have the larger radiator AND (when you look in the parts book) HD front torsion bars.
The other components of the HD suspension option would be "High Control Shocks" and more leaves in the rear leaf springs (see FSM for details).
The wagon, depending upon options mix, would probably have had the wider 3" brakes, from the factory. BUT our '66 Newport came with brake drums that allowed the upgrade to 3" brake shoes, so this would be something you'd have to check on your car. IF there was a separate option for HD Brakes, they would have been the same as the Police brakes, which were also non-self-adjusting brakes, which might explain why many dealers didn't order them.
I don't recall seeing any Chrysler products with power steering coolers until years later, but as small as they tend to be, the only real advantage might be more fluid capacity and slower degradation of the fluid by this situation. But in many later cars, the "cooler" was just a length of additional tubing that was secured to a "heat sink" of the chassis crossmember.
There was also a HD Signal Flasher to handle the additional load of the greater number of turn signal lights. But these could be added afterward, too. These flashers usually had a more authoritative "clunk" when they cycled.
There might have also been a factory-supplied trailer hitch that was available, but I suspect these were deemed a little weak as they were bolt-together as all of the aftermarket hitches were all of welded-together construction. The holes to attach the hitch to the car were usually already there, for the Class I hitch. The Class III equalizer hitch was what was used to haul house trailers with, which transferred the trailer's tongue weight to the whole rear section of the car not just the rear bumper area. These would be welded to the car, in many situations, from the literature I saw in the later 1960s.
Rear air shocks were just emerging in the '66 time frame, so the rear shocks might have been changed to the "Load Leveler" coil-assist style, or rear Air Lift (brand) rear air bags to not sag the rear suspension under load. There were a few other "spring assist" add-on spring leaves that were available back then too.
The wheels would have been 14x6 HD wheels, too, or the one year 14x6.5" HD wheels (station wagon specific!). Tire size on the Chryslers was 9.00x14, too, which makes the clearance between the tire and quarter panel somewhat tight, by observation.
At this point in time, it might be hard to document many of these things on your vehicle, "from the factory". The main things that somebody would only have altered for specific situations, usually, would be the rear spring assemblies, as they normally were not "consumables" that would be replaced or upgraded as "normal maintenance".
On the subject of the rear springs . . . the normal rear leaf springs had a fiber insert at the rear end of the springs for two purposes. One was to make them slide upon each other smoother. The other was "anti-squeak" reduction. On the HD Rear Springs, these inserts were zinc-based rather than fiber-based, which would be a visual difference.
With time and use, the fiber inserts would wear and deform and start to work themselves out from between the springs. They had a pair of plastic locating dowels that indexed with two holes in the rear of the leaves. These are things normally not noticed unless you know they were there. To replace them, with the car on a body-contact lift, you used a pry bar to separate the two spring leaves, knocked the old one our (if it was still there) and slid the new one in in its place0.
So, rather than a comprehensive "tow package" as most makers had by the end of the later 1960s, in the earlier years, it was a specific combination of options that did the deal. Factory a/c in combination with "HD Suspension" got the springs and shocks for the particular model taken care of, plus larger radiator and related internal automatic trans cooler. The brakes were usually already adequate for the basic "Class I" hitch use (generally 1000 lbs).
The HD flasher could be sourced from the auto supply, but the trailer wire hook-up would be done at the trailer sales place (or similar) as it involved splicing into the factory harness. Trailer brake controllers would be done there, too.
There was also a generally-accepted maintenance schedule for trailer use, too. It was not until the later 1960s as power/torque increased and the design of trailer hitches improved that allowed the pulling of even longer and heavier "house trailers" (later "travel trailers") that had all of the comforts of home. Precursors of the later "Motor Homes" and customized busses. When fuel economy issues progressed, light-duty pickup trucks became a better tow vehicle option as trailer weights increased to what they have become in recent years. And as the progression of "car-like" trucks continued to what we have today.
Decoding the data plate on the fender skirt, under the hood, might have some more cues of optional equipment.
CBODY67
