I believe the light fixture is secured with 3 screws and then the chrome plated outer ring is snapped on. Probably held in place with lots of sealant.
Chris & Maria
2012 36RL, Full Body Paint, Dual Awning, Dual a/c, Splendide Combo, Fisher Paykel dishwasher, 6.5kW Onan, Goodyear G614's. 2015 F550 6.7l, 4X4, Lariat, CC, 176" WB, Long Box, B&W Companion