2001 EXC have the same cooling system regardless of a 4 stroke or a 2 stroke, this technology have stayed until 2006

Here is the manual for 2006:
https://www.ktmdealer.net/uploads/models_tech_datasheets/8303F3_OM_EN.pdf

then your water pump assy should look like this

http://www.ktmcyclehutt.com/ktm-parts/productimages/77335955044_lg.jpg