[GMCNUT]

Thanks Ken - so here's what I ended up doing - I didn't like that the 63 Chevy switch comes with wires colored differently than 64-66 but decided to try it anyway, and it did install fine and I re-used the original upper column bearing from the GMC switch to fix that issue. 64-66 reproduction switches come with this bearing and horn contact but apparently the 63's do not. So after installing this switch, my brake problem was solved, but now when I turn on the Right side turn signal, BOTH rear lights flash - the drivers side flashes normally in the left position. I can only assume this means the brand new turn signal switch is faulty out of the box and there is likely no fix other than to order and install yet another just like it.