Bill-- I've been trying all day to get a decent picture of that mess.
Try this one-
The exit 'hot' water from the cylinder head is inch and a half galvanized at top. the flow is to the left and outside into the top of the radiator.
The inch and a quarter galvanized at the bottom is Teed into the propane tank coolant tank that adds ten gallons to what would be a fizve gallon system. The radiator holds four gallons and the engine holds one.
The stand pipe coming up the side is a 'sight glass' to show coolant level. The top of the sight glass Tees into the top 'vent' tube that catches bubbles coming from the engine and diverts them away from the radiator.
The head has a 195 degree t'stat installed. It takes twenty minutes under load to cause hot water to travel up the exit pipe, but in five minutes of operating temperature the entire pipe is hot. After about three hours of running the bottom 'entrance' pipe shows 85 degrees. This return water seems to equally split at the Tee and some travels into the storage tank.
After ten hours of running the return pipe is 100 to 110 at the engine and the storage tank will be from 100 to 160 depending on level. The top of the filler neck is hottest right where the overflow is.
The radiator stays about 170 at the top and 120 at the bottom. This is with mid twenties air temperature, but no wind.