In an excerpt from an old article on the fomoco website
HERE it says the XR wagon was designed especially for Australia and different from the US version. I'd never heard this before, now it's not earth-shattering, but it is of some interest! Here are a couple of photos:
XR
US wagon
You can see the longer rear overhang of the US version, but I'm not sure what else was done. This is similar to what was done converting the Ranchero to the local Falcon ute, where the rear overhang was shortened for better clearance (departure angle in 4x4 terms) although the Ranchero was based on the 2 door sedan and thus the rear of the cab was also further back meaning the tray length was not sacrificed but rather improved loading capacity by moving the load forward over the rear axle.
Note the different tailgates on the US wagon, I'm not sure if we had both here but this was the year before they introduced the 2-way tailgate ("Door-gate") on the full-size wagon.