Hey Guys

Hey guys I'm new, just bought a 87 Montero 4cyl for cheap 4x4in. As my 06 dodge ram 4x2 that gets stuck in any soft sand.

I can't figure out the oil pressure sender. My original one is intermittent and the guage sometimes works and sometimes doesn't. I tap on the sender and it works then later dies. I bought a new one from Autozone and the new unit only has one lead for a wire and the original had two leads. One for the guage and one for ground. When I connect the new unit it pegs full pressure with key on position then when the engine starts goes back to zero and stays there. Any ideas? Wrong unit? It's listed as the. Correct one with the montero and the raider in autozone and oriellys computers.