I should have searched for "thermistor" then shouldnt i
Try this number...
552.4.004.2A Thermistor
This is the sensor located in the oil screen plug. Again, for a 2000MY 900SSie. I assume you are talking about the fuel injected 99 model and not the FE ? (not that i imagine there would be a lot of difference
(just for a quick query sake, i looked up the same part on a random model, 800SS 2003MY and the part number is identical... "552.4.004.2A Thermistor")
Cheers!
ps: just looked up a 98MY 900SS and it does not appear to have this part... not to say the FE doesnt...