Water pump repair

I had to replace my water pump due to a leaking seal....
Mr Nissan wanted $800 for a new one, since they come as a singel unit waterpump-pulley-thermo/fan coupling.....
As it turned out, Mr Repco has aftermarket replacements for just $209 amde by GMB, so I replaced mine.
However, since I'm annoyed about waste, and curious - I decided to dismatle my "undismantleable" pump and find out how it was put together...
THe thermo coupling comes apart with just 4 bolts and is sealed with a high temp silicone O-ring. I should have measured the silicone oil inside it when I opened it, but didn't - but memorised a good image of it's level. The oil is still available form Toyota and some cooling specialists.
Next, I pressed the fixed thermo coupling housing off the shaft, only to find that the end of the shaft is actually peened over - slightly damaging the nurling on the inside of the diecast housing (but I think it is still OK). The next person to try this should therefore gring off the end 2 or so mm of the end outside of the coupling drive shaft until you see the diecast camfer behind it.
Then I was abvle to remove the pulley (4 bolts) and pull out the bearing locating wire loop from the side of the waterpump housing.
I then ground off the end of the shainless pressed sheetmetal impeller, since the original is completely closed, and I needed to push on the shaft to press it out. I then pressed the shaft including bearings out of the impeller and cast iron pump housing in one go. I found the cracks in my mechanical seal and am quite confident that I can get a replacement for it from a domestic waterpump place or car replacement shop. THe whole thing should go together again - I'll report agan when I've had a go at doing that too.
I noted that the replacement pump impeller was open at the end, and the bearing shaft clearly visible and apparently not stainless! I guess the end will rust - but do no harm in that spot - so the repaired pump can stay the same....
Cheers,
Joe