72 suburban Black wire (not ground)
 

Putting engine back in I find a black wire in the engine harness which I forgot to mark. It is in a small bundle which contains the pink solenoid wire for carb .
It appears that I was using it (ring terminal) but does not appear to be a ground (9.3 m ohms)and does not come to the firewall bulkhead connector. Any help would be appreciated.