It does have numbers. They are very small, on the left edge of the guage. You can see them if you smash your face up against the wheel. The numbers are in Centigrade. For more details look at these threads.
http://www.pelicanparts.com/ultimate/Forum3/HTML/009129.html
http://www.pelicanparts.com/ultimate/Forum3/HTML/012326.html
Tom
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82 911SC Coupe