Scosche FGA Floating Ground Adapter
1992 Ford E Series
Crutchfield Customer Review (What's this?)
Worked on 92 e350 rv. Right rear ground color code used for adapter for all grounds.
Pros: Straight forward
Cons: None for me. People talk of freq limits but most new radios have eq settings so compensate for transformers on factory wiring. If ur that picky run additional grounds.