Hello! I have been working on my dads 1855 Cockshutt. We put a 5.9 cummins in it a few years ago. My problem now is it seems to be leaking from the output shaft at the coupler cogs. Is this possible?It only leaks when it is running. It seems to be leaking between the cogs? Spraying atf everywhere. I'd like to make sure what is leaking before I take it apart. Thanks, Sean.