Originally Posted by
bzcat
If it is ticketed, I honestly wouldn't worry. You probably will arrive in T4 and depart from T4... that transfer takes minutes.
AA will do your passport check at STL and your checked luggage is doing airside transfer and not passing thru security screening again so that's enough time.
LAX-SYD has lots of connecting passengers... AA is not going to shut the door and dispatch the plane if they can see your connecting flight is already on the ground at LAX.
There's not much you can do other than keep HUCA. A good agent will have no problem moving you to an earlier STL-LAX routing (but good agents can be hard to find these days).