Stop in for a cup of coffee

I have a question. just dawned on me. My 76 dart sport rear axle. 8.25 limited slip.
the diff cover has no typical rubber plug. It has a big plug in the housing though,1/2” drive ratchet to remove it. It strikes me as odd.
Pretty common, my Jeep and trucks are all the same way, I actually prefer that over the other style.