i'm confused - QF115 seat allocation

[Tejas]

hi guys
i'm flying Bris - LA - JFK in May, having just requested a window seat in my online booking. According to the flight it's a 747-400, and i have been allocated seat 39K on the first leg. the thing thats confusing me is that i went through the seat maps and 39K ether:

does not exist - row 39 gets skipped, Or:
is in premium economy. this is what's confusing me tho - i doubt i'd get an upgrade now (i don't depart to may 5)
the booking for Economy (s). I'm confused (like normal). maybe someone could shine some light on this?

 

[oz_mark]

39K exists as an economy seat in the 2 class configurations of the 747-400's.

 

[NM]

39K exists as an economy seat in the 2 class configurations of the 747-400's.

And QF115 is always sold as a 2-class service, so that is the normal aircraft type used for the flight.