Technical 1955 Oldsmobile rocket 88 rear brake hose bolt

I'm using the engine & drivetrain from a 1955 Olds 88 in my build. this is probably a dumb question, but the mounting bolt for the "T" fitting on the rear axle has a hole through the center of the bolt. Is this correct? is it for a vent? Seems like it could let junk into the axle housing. Any advice would be welcome. I've searched the service manual, but found nothing.

 

Vent, Don't know about Olds; but others usually had a tin breather cap on them and later years went to a hose and plastic breather mounted on one of the rails.

 

Thanks. I figure I'll put something on it to keep crud out.

 

X2, that is for a breather. It is needed as heat expands the air inside the housing, otherwise you will have increased pressure causing seal leaks.

 

Yep it's a breather it may have had a cap on it or a hose that ran up to raise the height to keep water out.

 

Thanks again. Guess I'll have to construct something to keep the vent working & keep bad stuff out.

 

Any 4x4 pick up in a wrecking yard should have a hose and plastic vent cap attached to both diffs.

 

Lots of Ford products had the bolt with stud on top for a hose. Then you need something to keep the junk out. There is a plastic one used by several manufactures that will work. Used in axlehousings and auto trans