Royson,
I would fly with the OAT gage on my airplane too, even if the paperwork is not right. Many FSDO inspectors wouldn't make a fuss over it and it is just a gage. Major repairs on a wing (which is primary structure) is a different story. If the paperwork is not right on this (no 337), the FSDO inspector would take a dim view and maybe ground the airplane until the problem were rectified. Maybe that is why the airplane has been for sale since July. A nice airplane still, but I am going to move on - I did send a message to the owner that he should rectify the problem (though I am still interested) two days ago. Normaly, he responds in a few hours, but he has not responded this time.
It is hard to find a low time 150 in the Chicago area. I am not willing to go to a distan state (like California, Floriday or Colorado) to find a plane; it just is not worth it. I will look in Wisconsin, Michigan and Indiana (Ohio is a stretch).
Thanks for your message!
Steve