I just serviced the heat exchanger on my QSC. The Cummins coolant petcock is the same as those used on old radiators with no hose connection so I have to drain the coolant into the engine pan and pump it out. Same goes for the distilled water flush. It turned out the thread on my old Yanmar petcock with a hose connection was the same so I replaced Cummins fitting. The hose connection is 7 mm so I bought the short piece of Yanmar hose and used a 1/4 hose barb to connect a longer piece of 1/4” hose. The 1/4” hose wouldn’t fit directly as it’s a touch too small. Now I can drain the antifreeze directly into containers. Works perfectly.