Greets!

The ones across the middle and ultimately covered with damping. In acoustically small cabs for the intended BW, bracing orientation is irrelevant since there's a ~uniform particle density that just expands and contracts, but as the cab gets long enough in one dimension to make it have pipe action, then it begins to matter. Probably not much in a rectangular cab such as yours compared to a thinner, higher aspect ratio cab, but it doesn't hurt and pointing this out whenever appropriate hopefully will get folks to think in these terms when designing their own.

GM