G'day Troy,
some earlier GU patrols had insufficient earthing that caused various problems, particularly if you were using the body as the earth return. We solved that with our patrol by fitting additional earthing straps between the battery, body and chassis. Later models (we now have a 2007 CRD) don't seem to have the same problem, but we have still fitted extra earthing between the body and chassis to assist the HF antenna.
Regards
John