New guy did not go south - just had my head under the hood and in the dashboard for a while!
The schematic I am referring to is that which is in the GMC shop manual for my vehicle - it most definitely lists 'HW' - perhaps the shop manual is different than the "official 55-59 GMC manual schematic" someone referred to.
I'm not using an aftermarket harness but trying to do things the way the factory set it up with respect to color, gauge, etc. I've checked the manual and there is no index for abbreviations so I'm thinking this was a 'rogue' draftsman or engineer.
Any way, thank you for the input.
