Oil Sensor

:(

i have just switched engines in my 1994 chevy s10 and I have one plug I cant find, im pretty sure it goes to the oil sensor because everytime that I turn it on the oil pressure gauges instally shoots over 180 but it runs fine and sounds great I was wondering if someone could help me out and tell me where I have to plus it in, I have no idea where it goes ive spent about 4 hours looking and there no outlet on the oil pan for it.