Neutral safety switch

I posted a thread earlier this week regarding a starting problem and thanks to everyone's feedback I'm fairly certain it's the neutral safety switch because as soon as I move the column shift to neutral it fires right up! I found it when I was under the car today and I'm gonna have a helluva time getting around the H pipe exhaust that is actually welded to a hanger close by, to get to it. I've been hesitant already because when I bought the car I forgot to ask the previous owner what tranny fluid he used after he rebuilt it. I've read several opinions on this forum and it generally sounds like dexron 3 is not gonna hurt anything, but I'm not sure if I might be mixing it with a different fluid he may have used? If so, what could be the effect? Also curious as to how much tranny fluid I can expect to lose changing the the neutral safety switch? Thanks in advance for your feedback!