Man, this is not going to be a small job...
There was a small leak late last fall. I just nursed it along, topping up with water as needed. Not any more! Pour water into the radiator, and it pours right back out the pump (see garage floor, above).
I swear the last water pump I replaced took half an hour, tops. (MK1 Rabbit/Golf? I forget.) This one's buried - going to take a while.