Eel diablo has issue with the shaft having wear. His still leaked even after he replace the seals twice. Maybe he can chime in on the details the work was done by Jerry so maybe he can also comment and have a more detailed explanation.
The LT250 and LT500 water pump seals are constantly being replaced but the mechanical seal is seldom the reason for coolant leaking out of the weep hole.
There is a design problem where the aluminum impeller sits on the water pump shaft. The shaft has a very small contact patch where the impeller sits and imbeds itself into the soft aluminum impeller. When the shaft imbeds itself, the torque on the impeller bolt lessens, allowing the the special rubber faced sealing washer to loose contact with the sealing surface on the impeller. When the rubber sealing washer looses contact with the impeller or the rubber lip where the bolt goes through the impeller bolt is not sealing, coolant will leak from the weep hole.
If the water pump shaft protrudes above the water pump impeller the rubber faced washer will not seal against the impeller causing the weep hole to leak.