I got one of those lights and it is the correct diameter to fit the holes. So, I'm all set I guess. Just have to buy about 20 of them to replace all mine. And several tubes of silicone sealant.
'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