Rear axle nut size on 2003 dually

Can anyone chime in what size the nut is on the rear axle of a 2003 dually? I changed the rotors and brakes on my 2001 dually last week and it looked like it was a 6 round 2 9/16. I improvised with an old tool (which involved grinding to get it to fit the narrow opening) to remove them on my 01 but I would like to get the right socket for when the time comes to work on my 03.