I am not aware of any differentials that need them with a stock horsepower engine. Off road in low range, maybe.
Just don't set them too tight.
Stock engine = no real need,
except certain Dana 70 rears in some Cummins Dodge trucks, but even then the cover only helps a little bit.The screws do NOT get tightened much
, i think only 20 inch lbs? it is very, very little. More torque just distorts that caps!