trying to solve Noise

I have some alternator whine in my vehical.  I've read many many many articles on things to check and how to fix.  This has reduced the problem but not eliminated it.  The last thing i checked was my rca ground's.  I have <1 ohm from my rca cable jacket to chassis ground.  In the article i read... this is a big problem.  I can't seem to trace down where the "ground" is getting introduced to this cable.  The cable is not touching chassic ground anywhere.  It is only hooked up to my head units rca outputs.  I have the Kenwood 7015.  Anyone got any ideas how to isolate my rca's from the vehical ground or is it ok to be that way?  Anymore suggetions on solving alternator whine would also be appritiated.

Thanks in advance!

What is a muting plug....?  I feel i should know after messing with car stereo's for years.

Thanks

To make a muting plug, cut off the end of an RCA cable, and short the two conductors together.

http://www.davidnavone.com/MutingPlug/Muting2.wmv

If you don't have a high speed connection, go to the bottom of the page here.  (A picture is worth a thousand words)

In fact, over the next few days I'm going to make a few muting plugs out of some old RCA home audio connectors before they get tossed into the trash.  And these connectors date back over twenty years for some of them...quality is not an issue in this case!