Hey this is just a FYI. Long time Ford owner, first time 67 Mustang Coupe owner. I found this site trying to troubleshoot a neutral safety switch issue. I was having intermittent starting problems, so, I replaced the nss with new after market one from a respected supplier. Still would not start. After week of no success and trying many different solutions, I put the old nss back on and it sort of worked but not consistent. When putting the new nss back on I noticed the wires in the new nss wiring plug was backwards. Reversed the wires and everything worked fine. Egg on my face, I should had double checked the wiring, but I had juice to the the backup lights and the shift indicator light. Anyway keep that solution in your back pocket.