Will not start in neutral at times either??

[72timemachine]

Just to bring you up to speed, I had to replace the ignition cylinder lock due to the fact that the thumb tab ring snapped off and it felt like the key was going to break off each time I went to start the truck. I have about 2000 miles on this new cylinder so I do not feel this is the problem.

I have an 84 c3500, 6.2, th400, with around over 300,000 miles on it...runs like a clock. However, recently when attempting to start it the past several times it would not crank while in park....so I dropped it into neutral and it started right up. At other times it will not start up in neutral unless I shift it back to park then into neutral. Do you feel it is time for a new neutral safety switch or it may just need an adjustment? My starter is new and spins up great so no drag on the system there.

Thanks for any help.