I have replaced the water pump on my TO 35.
I took the old pump with fan hub to a machine shop and had them press it off.
Be sure to measure the distance from base of old pump to some part of the fan hub.
As you must insure they press the hub to exactly the same distance on the new pump, other wise your belt may not line up.
I was told that many times the fan hubs break during this transfer, so be prepared to buy a new hub.
The machine shop told me going in, that if it broke they would not be responsible and ask if I still wanted them to try and get it off the old pump shaft.
It did work and they were able to press it onto the new pump.
I got my pump at the MF dealer.