Easier way
You have to dig out the mechanical seal that's right behind the impeller. You will also have to buy a new mechanical seal AND the special tool to install it. It's a pain, but it is doable. You can get the mechanical seal, inner seal, cover gasket and the tool here:
Indy Specialties
Hey Rich..... There is an easier way then digging I out.
Mind you....... The motor must be on the Bench.
You tip the motor upside down...... Find the little 6mm waterpump bushing locator screw.
Heat the case on both sides around the screw to loosen the Loctite and remove it.
Now with the oil pump removed you can push the shaft out towards the water pump from the oil pump side and the seal pushes right out.
This is how we get them out without marring up the case.
When reinstalling the brass boss use a black sharpie to locate the screw hole.... Deburr it first...... Tap it in place then add a touch of blow Loctite install the shaft from the oil pump side ... ( don't Forget machined spacers ) any parts website will show you locations.
Then for installation........ We bolt a flat stop plate onto the oil pump side so you can press the rotary in..... Or tap in with dead blow hammer ( I don't like this one ) but have seen it done..... And it works.
Keep in mind it's a polished glass faced seal....... Very brittle.
If the motor is in the sled the the dig out way is most common.... SUCKS !
Dan