In the parts diagram #12 is the portion that screws into the block, and #13 is the portion of the drain you unscrew to drain the block. The second nipple is to attach a hose to drain the block. It was likely used in the 1uzfe motor in cars, which uses most of the same parts. I don't think any one uses them in the boats as, unless you have closed cooling, as you are just draining lake water into the bilge when you winterize.
Based on what you drew earlier, your #13 has a t handle on it. If #13 is backed out, water from the block/lake will drain into the bilge, you should be able to screw it back in and solve your issue, though as I said earlier, I,d unscrew it all the way and make sure it's not damaged, then screw it back in.