I have a 6 H.P 1991 Evinrude, model E6REIA. I am planning on changing the water impeller during the winter months here in mich. Just wondering if I can just drop the lower unit to do this or do I need to remove the power head to do this job? I did a few impellers in the past but never had to remove the power head on any of those motors. Anything I should watch out for that is unusual on this motor while doing the impeller? Thanks for your input.