What's the access port on top of the diff? 14mm hex, 5mm allen, 10mm socket, what?
For the vent? Vise-grips, in my case! It's a round barrel doodad that vaguely resembles the old-style fuel primer pump. It may have some flats on it, I forget, and it has a crimped-on cap with ears on it that are open on the bottom. -- Jim
