@OR VietVet - Hopefully you can help my memory here...
If memory serves correctly, the water pump bolts to the timing cover, and there 2 water pump gaskets, one on each leg, or a single large one, depending on year.
Then a timing cover, and gasket, that the coolant also passes thru, that mounts to the front of the engine block.
On my last 3800, the timing cover gasket is what had failed. It took me forever to figure out too, as I wasnt there to fix a coolant leak, but a power steering leak, that I had to dismantle all that to get too. Only found the issue after reassembly.
It can fail and leak internally, or externally. So if you are not getting a chocolate milk oil, consider yourself lucky! When it fails externally, it can be hard to trace, as the belts, pulleys, accessories, and harmonic balancer throw the coolant everywhere.
When mine failed, it would not leak when cold, but only when the engine was up to temp. Metals expanding/contracting. I mention this because if you try to find the leak by putting pressure in it, it might not leak.. But it also might.