The bulkhead fitting one on the left is the return line from the top tube on the heater core. I cut the end of the bulkhead fitting off and welded it to the bottom of the remote fill tank. The one on the right is a 90 degree bulkhead fitting and it goes to the rear port on the water pump. A 120 degree AN fitting would have been a little better than the 90 here. I had the blue ones on hand already... couldn't bring myself to buy more fittings for something that is not normally seen.