Make sure the brake light's not telling you the truth.
Ensure you're good on fluid in both circuits front and back.
I can't remember the details on that switch, though.
I'm not really sure about the neutral safety switch, but on my '87 Silverado it was a white, flat, sliding switch down on the steering column.
They were a common failure point and my reverse lights didn't work either.
I know my information is wonky, but maybe it'll point you in the right direction enough until someone that knows something comes along.