Because so many thermostats were not fitting, I ordered two more in hopes one would fit. The Rock Auto thermostats was just like the OReillys one. It was too wide to fit in the housing. Rock Auto has an unfair return policy. They make you answer about 20 questions, and then they say Is the part we sent you the part you ordered? I say Yes, but it didn't fit. Then they say OK since we didn't make a mistake, we will not refund the shipping to you. So their policy is they don't stand behind their products. Luckily, the old NAPA 155 in an old box did fit. I got it on Ebay thanks to Farmer Jon's tip. Thanks Farmer Jon!