Checkmytrip?

Online checkin should be available for your flight.

Start the checkin process, and change your seat. Check how many rows the plane goes back... 30 and it's a 73H, 24 and it's 73G. You can cancel the checkin process at that point if you want.

There are other ways too. Don't rely on Expertflyer or other tools to tell you though - They often seems to give me incorrect information.

See also http://www.virginblue.com.au/helpInfo/travelInfo/duringYourFlight/index.php?section=Seating

 

bambbbam2 - As Mal suggested use OLCI and select a seat. DJ mainly has 738's so most will be 30-row configs.

As I posted in another thread, the best Blue Zone seating (extra $30.00 cost) is row 15 (on a 738) but you will be last off the plane. No big deal really but it can be annoying. Rows 1 and 14 are also blue zone on a 738 but row 14 does not recline. . Row 1 has fixed armrests and smaller tray tables.