'56 olds rear end brake fitting-hole in housing-cover?

[Guest imported_pete324rock]

1956 oldsmobile.-I hope I didn't lose the cover if there is one but can anyone tell me if the brake fitting that attaches to the rear end housing which has a bolt -star shaped-that has a hole in the middle that goes through to the rear end-I suppose for pressure relief-has a cover on it.Can't remember from last year when I took it apart.Can't imagine it being open to the air.thanks pete