Replacement stereo for 2018 Gulf Stream Conquest

swing over to crutchfield.com and see if any model's looks jump out at you. if your 450 has a factory head unit, or at least a DIN mount head unit, should be easy to find an upgrade for it.

if you have steering wheel controls (radio, phone, etc), some but not all will have a CANBUS interface box/module (usually for extra $) that will talk to those as well