[lumen8]

Well the TX valve isnt the exact same thing as an orifice tube, it does a similar function, but it is two different ways of doing it. TX valves look like a block of metal with a temperature probe in them.

The AU/NU/DU fairlane when looking underneath is basically an AU falcon sedan with an extra piece added in the floorpan , including little chassis rail extensions. You can clearly see the extra bits added to the existing falcon floorpan and chassis pieces when you look at them both on a lift and compare.

Outside of this area, you will find it is identical underneath to an AU falcon, the front and rear of the chassis.

The wagons are different in the rear chassis rails, they are a different rear, although yes from the outside the rear doors and rear quarters on the wagon are basically fairlane. But the rear floorpan isnt.

The wagons have slightly different rear chassis rails, different fuel tank, different rear floor between the rails, the fairlanes (like the AU falcon sedan) have the spare wheel well shape in the boot floor... whereas the wagons floor is about 2 inches taller and flat, and the spare ratchets on from underneath similar to the utes.

So in summary id say the fairlanes are an extended AU falcon sedan, but with wagon rear doors and its own unique roof and C pillar.