Brush Hog Needs New Seal

[hblosser]

I have a 30 inch brush hog that turns counter-clockwise. It is old and is leaking oil badly. I need to replace the bottom seal but don't know how to get the top nut off. I has a disc-looking nut that has two holes in it. Is there a way to get it off without a special tool?

 

[RichardTX]

I think you can use a punch and a hammer but it has been far too long since I disassembled one to say if the top nut is a RH or LH thread.