I'm going to replace my factory stereo with an aftermarket one in my 2004 Alhambra 1.9 PD SE. Does anybody know if it is just a straight swap or do I need something for the aerial (I have read there is an amplifier on some in the base but to be honest I don't know where my aerial is). Also, I've read about terminal no.3 (K-line). Would this need isolating. Thanks