[GMCNUT]

Thank you Ron - so when you say the Chevy switch does not work in the GMC, let me clarify that my GMC is a 1000 series 1966 model, so the 1963 Chevy switch was recommended as a means of getting a switch that would fit the GMC upper column housing. This does work, and all lights work now, but when I click to turn on the Right turn signal, both rear lights flash. Its a brand new switch so not sure why this is. The old correct original metal GMC TS switch I removed would work in the right position prior to taking it out, and only the right side would flash as it should - so the variable and "what changed" here was me installing the 63 reproduction Chevy switch - thus, it has to be the problem. The switch I installed had all the wires pre-configured in the clips so I inserted them into the female under dash connectors with no mods and all the wires do correlate to the diagram you provided (thank you by the way). So I checked and the Green wire in the factory truck harness is indeed connected to the Violet wire from my new Chevy switch as shown for the right turn signal so this much seems correct. I think the problem is in the top end of my new switch - a buddy said they ordered and installed three switches in another guys truck before they got a good one that worked straight out of the box, so I may have got a dud here - can you post pics of the NOS switch and harness you have? I may buy it to fix this issue I have rather than buy another aftermarket one. I also have a 1963 Chevy that needs a switch, so if your NOS one is a 63 GMC switch and will not fit a 64-66 GMC upper column housing, maybe it will fit my Chevy?