Thanks, saw that but it does not have a check valve. Rev extreme has one that would work, with cv, but mates to a gm cover.

With the mcmaster being 3/8, I may mate a spectre 3991 to it.

My objective is to keep the crankcase from being pressurized hence the check valve to allow air out, but not in.

Still cold out, have plenty of time to decide. Keep the options coming.