I'm missing this nipple on the thermostat housing on my B18C. There's a hole for it. I can try to source one from the junk yard, but I can't seem to move them. Any tips on how to remove these nipples? I'm afraid I have to buy a new housing.

The diagram from the GSR shows it connected to the upper water outlet on the head.

The nipple in the green circle is what I'm missing.

 

Just get another thermostat housing for your application. I actually have and had the thermostat housing on my motor just a few days ago with the nipple. I needed to get one off my friend that had no nipple.

So if i can find it in the garage tomorrow, i will PM you.