Hi, i just went to Napa to get a 180 thermostat, that im gonna intsall with my chip, well, it has nothing on the box about it being a 180. All it has is a part number #139. So i entered the part # at napa's website, and I got 3 different t-stats, two 180's and a 196. How do I know which one mine is? O yeah, do I need a new gasket for it?