Be sure to tell us what model '55 you have. I am not familiar with Task Force trucks and might make a difference, although I doubt it. Regarding the 3 prong connector for the headlight harness, one of them is a ground. The ground will connect at the inner fender panel (at least on Advance Design trucks) and does NOT go to the dimmer switch.
The dimmer switch has 3 connections; one for the battery hot wire, one for low beam and one for high beam. Functionally, it doesn't really matter which headlight connection you hook to, except that you may not be synchronized with the high beam indicator bulb on your instrument cluster. If it is wrong, (you have a 50% chance randomly doing it right!) just switch them.
If you have no dedicated ground connection on your headlights, perhaps the headlights are seeking a ground, heating something up explaining the smell you detect.
Kent
