Replacing Factory radio with Kenwood Double din

I am seriously thinking about replacing my 04 impala's factory radio with a Double din Kenwood 7017 radio. My friend has one in his car and we measured the deminsions and there is plenty of room in my dash for the unit. I hear that the mounting is completly different so the radio will not fit. Has anyone been successfull putting an after market double din radio in an impala if so how difficult is this to do?