Disregard my previous post about the PAC Audio products. They seem to complicated and I'm unsure if it will retain RAP and interface with the Class 2 Data Bus.

These are the products we use at my shop, without any problems.
Use this instead:
http://peripheralelectronics.com/pro...563&strSearch=

Also this is a quote from the Application guide:
"These vehicles have a "Premium Bose®" amp that only accepts 2 channel audio inputs. OnStar® volume can be controlled via the steering wheel audio controls. The GMAHCM chime module is not required when using the BOSE® amplifier.
If you are not using the BOSE® amplifier, then the GMAH24 and GMAHCM interfaces are required. The aftermarket radio will not fade, however it will still continue to balance."

Dutch

Actually, BlackIce the Monsoon (at least in my '04) is not data bus controlled. When I installed my Delphi nav system, I used the 'Radio On Signal' from the nav unit to turn on the amplifier via the '14 Volt Ref' circuit (pin A3 on the Bonneville Dock-N-Lock). There is no Class 2 signal to these amplifiers. I'm pretty sure mine is Monsoon becuase that'* what'* painted on the case and that'* what my original HU indicated on power-up.

Looking through the FSM'* for all 2000+ Bonnevilles with the 'Uplevel' radio, it seems that '00 - '01 had the Bose (RPO U80) but '02 and on had the Premium Monsoon (RPO UZ. In either case, there is no data bus control to the amplifiers