Little back story, I noticed a vibration (underway getting on plane) around 1800-2200 rpm running my boat last season. I thought I had a prop that was off balance.

I ran the boat last weekend without props on the muffs and noticed the vibration is coming from the port side even in Neutral. I am in the process of doing exhaust and full hydraulic steering, I'm considering pulling the drives for inspection and new seals. What should I look for???