Engine arrangement is confirmed as 4N-3801.
Complete water pump for the above arrangement is 2P-0662.
The repair kit for it is 6N-9608, a Part Number that updates first to 1W-7046, then to 170-0558.
Note that the repair kit does NOT include the gasket Ref #2 and Seal As #3 (both necessary I would think) or the Impeller Ref #18 should you require one.
Thanks Nige for the information.
When I go to the Cat parts website and look for 170-0558, it shows 12 parts included in the kit. It looks like the seal #3 that you mentioned is included and is part number 262-4378 but the gasket #2 is not included. The gasket #2 is apparently 8N-5928 and is available. It looks like part number 262-4378 may replace items 3, 4 & 5?
There is also an oil seal included in the kit part number 154-4482 which seems to be the same as 8H-9520, #6 from the drawing.
5F-3106 (7 on the drawing) is an o-ring but not included in the kit, replaced by 175-7904.
Also, the shaft (part # 172-5188) is included. I have noticeable side play so maybe the shaft needs replacing. The impeller looks ok.
The Cat parts website asks me to enter my equipment serial number but for some reason it doesn't accept it. It seems to think it is invalid. I am entering 80H4888. It does suggest that it should start with 80H.