oil pressure sensor type?

I've got a 96 4dr vin W blazer and I'm getting erratic readings on the oil pressure gauge usualy at idle so I wanted to change the oil pressure sensor, but when I went to NAPA they said theres a 3 pin and a 2 pin sensor, does anyone know which one mine uses? I'de like to get it before I take it out.
thanks in advance

Why don't you pull the plug off and look?

well where is it located? I thought it looked like from the diagrams I have to pull the distributor off to get to it.