I would imagine you could pull 1 and start the engine.
If it squirts out, you know it is the radiator inlet side.
Some people use compressed air to flush the radiator portion.
I would probably just do a spill and fill.
Please post your results.
2018 Tesla Model 3, Medium Range Battery
2018 Lexus RX450h
2013 Lexus GS350 F Sport
2006 Acura TSX
2001 Tundra Access Cab, 1998 Accord LX, 1968 Corvette L36 Roadster, 1965 Olds 4-4-2