If possible, look up the data on the radio on the Internet and see how it is mounted into the hole. Sometimes there are concealed latches on the ends of the radio that hold it in. Sometimes a slim blade is used to release the latch, or it is part of the radio trim. Other than that, no clue here...
Sent from my pocket Internet using Airstream Forums
'The Silver HamShack' (2007 International 22FB CCD 75th Aniversary model)
Multiple Yaesu Radios inside and many antennae sprouting from roof, ProPride hitch
2012 shortbed crewcab 4x4 Toyota Taco TV with more antennae on it