PU Truck mag That answered a lot of my questions about these covers. Extra large ones may not make a lot of sense because they disturb the oil flow in the housing.
Do I need a dip stick if i keep an eye on the floor under the diffy?
Drain plugs? If I would happen to change diffy fluid ever 100K miles, I would probably want to get all the good stuff out from the bottom of the housing and take the cover off anyway.