I have a BOSE radio/cassette sysytem (factory) and getting terrible alternator noise when radio is on. I understand this to be a coomon issue with the Bose systems and in C4's. Chevy used to make a filter harness (part # 122485) that has been discontinued and I am unable to get anything else to silence it. Has radio and amplifiers checked and they are working fine. Does anyone know how to deal with this. I also understand that Chevy actually prepared a step by step manual for this but I cannot locate one. Any help, PLEASE!