Somebody else can post a photo. A fellow long ago by the last name of Hitchen used to sell a plate that screwed to the license plate light holes under the rear bumper. It spaced the rising exhaust gasses out another 1 1/2 inched to prevent fires such as this.
I think this is what you are looking for....It is a nipple screwed into the filler pipe, a rubber hose, a looping pipe and another small rubber hose. I have a drawing of the system, but you will have to email me for that. Coralsnake68@hotmail.com