So, today my upstream new oxygen sensor finally showed up after being help up with USPS. Anyway, I went out and took the old one out, and before I tore open the new ones sealed bag, I noticed the connector was not correct. I immediately came inside and looked up the sensor, which said it was for the 99 Mercury Cougar. SG226 is the part number. So, I did a little closer inspection of the pictures, and low and behold, there seem to be two different connectors used. Was there a change in years? Mine has fully round plugs, where this one was half round, half square. Even O-Reilly, Autozone and Rock Auto show upstream and downstream with both connectors fitting this car. Also, I have noticed some places saying the same sensor works as both upstream and downstream. Any thoughts to this?