Glad you've reduced your noise. My bevel box was due for replacement it was ok until 1300 miles then became very loud at 40-60mph. Then this happened.
The oil in the box was very
sticky and "possibly" caused the seal to go.
Box replaced and 2k later all ok.
When it leaks it really creates a mess under the seats and prop tunnel
Not sure how your warranty would be affected if a different oil has been put in? & if found out
