On the right side of the fan, at its base should be the engine serial number and engine type number. If you can find the type number, it should be 911/xx. When you find what number XX is, look it up on
this chart, compliments of
Thom F. who smartly lifted it from Paul Wier's web page after they went tits-up.
If you can't find the type code, post the serial number, and one of us will look it up for you.
Tom