Ok, here we go...
Antenna wire through the chassis was a smaller diameter on Z's up to (2744 and 3798 are my samples) than I've seen in later cars
Front bumper on 2744 mounts with a single M10 stud on each side, rather than the two on later 240's. The mount brackets are correspondingly different and made of lighter gauge steel than the later ones.
240 Gas tanks on the Canadian UA models have only two vent lines. The floor of the hatch then does not have a steel pass through tube for the left side, just a rubber plub. They also have no evap tank, hard vent line to the front, no "flow guide valve". Which also means the block vent tube does not have the little extra knipple, and the big end of the PVC hose is unique too. And the air cleaner may not have the nipple that attaches to the flow guide valve outlet. Not sure about that one, I don't have the original box on 2744 or 3798.
Horn mounts. One 3798, there is a 3 sided retangular bracket welded to the lower rad support that sticks out about 3/4 inch that both horns mount to. On 2744, these brackets are absent and you have the usual (in my experience) two M8 bolts that go directly into the lower rad support through the two horn bracket holes. Never seen these sticking out - brackets before. They are factory. As if there was something behind them that had to get clearance. Factory turbo intercooler? The car was not an automatic.
The change of where the rear brake proportion valve is located and all the tubing and tubing support bracket changes that go along with that
Gas caps
Brake master cylinders. Early had the Front reservoir in the front, with associated changes to the hard lines below.
Gas pedal rod in foot well with extra clevis-y thing on top for throttle control cable found on early ones.
Different style J-hook on the throttle actuation mechanism.
Different bell crank design early to late
Hoods. Early one with no holes either side of the latch. Also difference in how hood skin is wrapped around the top corners.
Inspection lid catch changes
someone else take over, I'm tired....