on that 4-class config 52 HJK are crew rest seats at the front of the economy cabin.
Note that rows 36 to 39 are PE seats sold as Economy. Very few of these are actually assigned at this time, but most are blocked. So keep checking and even ask at check-in.
Thanks Nelly
As lowly Silver, is there any point phoning Qantas or will they just tell me that the rows 36-39 are blocked?
Sarvo