Volvo Penta MD2020 - how to remove raw water pump

I discovered some oil was dripping from under the engine and located the leak to be behind the raw water pump. Between the pump and the engine there is a O-ring which should be easy to change. I thought.... Someting I have realised is the pumps is differently designed from model to model. They are differently designed and differently mounted on the engine. My pump was new and mounted by a mechanic when I bought the boat in 2016 but it was never painted. My plan is to paint the pump Volvo green and mount a new O-ring so the pump can run for many years. Parts : Original Volvo O-ring, part nr. 3580063 (3 US dollars)