The casting number on your block denotes a 73 or 74 Ford model year 351c block. It is correct for a '73 or '74 Pantera and is a regular production block with the CF, Cleveland foundry icon, and is not an "Australian block".
The standard 2v 351c would have the same casting ID of D2AE-CA but would only have 2 bolt mains. Some 4v Ford builds use the 2 bolt main blocks also.
The 351C CJ block would have the same casting numbers but have 4 bolt main caps.
The XE id blocks came about because the 4 bolt blocks under extreme racing stresses would develop cracks in the blocks webbing near the center main bearing cap and run up the side of the closest piston bores.
That indicates flexing or twisting in the block. The XE blocks are thicker in the bearing webs and where the oil pan bolts up, "the oil pan rails", are solid and not hollowed out on top of that "rail" like the regular production blocks are. So that in effect acts as a "reinforcing girdle" cast into the block to reduce or eliminate the block flexing under extreme stress of racing.
The cylinder walls are also thicker so they can take larger over bores.
So all of that good added strength adds about 35-40 pounds to the overall weight of the block.They definitely are hefty for sure.
Some credit Warren Trope for the existence of the XE block? He raced a Group 4 Pantera in the US. His father was a development engineer for Ford at the time. That led to internal influences at Ford. I can't image how that could have happened? 
Here are two pictures of the pillow XE block. The first was available about 1975 as a Ford service block and just had heftier features and the XE casting number. This one pictured has a 1977 casting date. It is thought by some that there is another special run made for NASCAR about 1980.
The "pillows" increased the water capacity of the block by adding pockets to the side. It is often referred to as the "pillow block" because of it's appearance.
Early on, the car magazines referred to these "racing blocks" as "THE Australian block" as they were all cast at Geelong, Australia and bear that foundries icon. Later as XE blocks and finally as "NASCAR BLOCKS".
At one point ALL "Cleveland blocks" were cast in Australia but not all are the XE blocks so that adds to the confusion.
They came about too late in the "development" of the 351c to benefit the factory raced Group 4 Panteras. They simply didn't exist yet at that time.
