I'll beat Blizz to this one. Make sure you get left side windows for the left side, and right side ones for the right side. And you might want to consider getting at least one of them that has an emergency escape feature. The emergency ones have a quick opening system to bail out in a fire. My t/c has both side windows emergency exit type. Gives me some peace of mind.
'03 Freightliner FL112, 295" wheel base, with '03 United Specialties 26' living quarters, single screw, Cat C12 430 h/p 1650 torque, Eaton 10speed , 3.42 rear axle ratio