I pulled the AC3 track apart. It's fake.
It's stereo in a 5.1 container. Also, the 5.1 aac in the 13.9gb (while also being real 5.1) is also less compressed than the ac3 from the 8gb. The 13.9 is still the best, even though it's slightly cut and has translation. You'd have to Frankenstein the two cuts together to make it more complete.