75 Duster Neutral Safety Switch... I need to replace it!

There is no clicking (then I would know its the starter, I wish it was that simple!!! haha)... I have replaced the starter cylinoid thinking that was the problem and now the NSS.

Its just silent... oil light comes on like it wants to start and I noticed this morning when I turn the key and watched the gauge marked "Alternator" the volts dropped way down, when I turned the lights on and off it went to the center point and started. Could this be an alternator or Voltage Reg problem?

What is "linkage" and how do I inspect that or test that? I am learning as I go fellas so thanks for all the help!

Replace the ballast resister on the drivers side firewall - it's a $5-$10 part - the white thingy.