1966 coronet starting issue

ok went out tonight to work on the old blue and my wife turns the key. Nothing. So I jumped the starter relay with the key off and it cranked, so turned key on jumped it and it started. So It's either the neutral safety or the relay. How do I tell which it is? Where can I by pass that switch to check to see if that is the issue? Will it require going under the car?
Also I see there are like 3 different relays that could go on this thing so witch one do I pick if that's the issue?
Rock auto has them listed as 105T 4 terminal, 105 2 terminal, 106 3 terminal

What you might need to know
1966 Coronet 273 auto trans column shift (and wiggling the handle does not work)

Thomas

clean the battery terminals first..ensure tight clean connection.

Already done

Thomas

The brown wire that goes to the neutral start switch on the transmission is basically a ground. Take a new piece wire and connect it to the post on the starter relay that normally goes to the neutral safety switch and ground it out in NEUTRAL GEAR and if its the neutral safety switch that is bad the car should start, if it doesn't then its probably the relay.

Awesome! Thanks

Thomas