Okay, so I’m hoping somebody out there knows what the black with a medium blue stripe wire is that is coming out of my wiring harness on the passenger side trunk wheel well. The car is a standard 68. The yellow wire next to it is for the fuel sending unit. I am curious if the black/blue stripe wire is supposed to be a ground wire. This is the situation. I replaced the fuel tank and discovered that somewhere along the line the fuel tank was previously replaced by a former owner. Problem is that the fuel tank that they put in the car had an incorrect fuel sending unit connection for this car. So as you can see, the yellow wire was combined with the black/blue stripe wire for the modified wiring for the fuel sending unit. The fuel gauge on the car did not work properly either. Also, the previous fuel tank did not have an XR-7 style fuel sending connection. There were two different styles for the 68. It looks like some kind of generic fuel tank was used with a generic connector to the fuel sending unit. The fit was almost spot on though, minus the different fuel sending unit connection of course. So with that said, anybody got any answers for me? Any help is appreciated. 
I’m not 100% sure, but I think it nay be for a C-pillar light. Do you have them and if not you should be able to find a corresponding wire on the other side.
You may be absolutely right, badcatt. Being that my 68 is a convertible conversion, it has no C-pillar lights. I will check the other side. Thanks! 