'96 o2 sensor wiring

Got a '96 Metro the other day. The o2 sensor was cobbled as is a lot on this car that I'm working the bugs out on. Anyway the sensor has 2 white,1 gray, and one black wire. The car has 2 black, 1 white, and one blue. How does this need to be connected or is it the wrong sensor. Don't have a lot of cash but will buy a new one if needed. Thanks for the forum and the input it sure helps me out a lot.