Alright, here's a pic of the duckbill, of the two missing out of mine it's the smaller wire on the left:
And, on my 1990 W250(your truck *may* have different colors) it goes to this wire. This red wire, the one pulled out and with a knife pointing at it towards the edge, goes into the drivers side of the firewall bulkhead:
This is the battery hot that goes to your keyswitch, and looks to be your problem.