Valve cover hole

[fireguyfire]

My 1970 383 had a bunch of next day parts on it, including aftermarket chrome valve covers.
I bought and installed a set of factory covers from a guy as I want the engine to look stock.
On the rear of the passenger side cover there is a large opening with a grommet, and I am unsure what it would have been for.
Can anyone tell me what this opening would have been for?

[JS29]

A breather with one hose going to the air cleaner. 

[docmel]

That looks like for the large type breather that had three nipples that were welded on it for 3 hoses that attached to it.  I beleive one hose went to the air cleaner , the other two I cant remember  (maybe one as part of the evap sustem)?. These hoses were rather large in OD and tended to clutter the engine compartment so people tended to get rid of it later on and replaced it with a push in type breather. 

These three nipple push in breathers may be a little hard to find, but a searh will find you one:  I dont beleive these OEM breathers were e body only parts, and I think many same year moprs used them, even station wagons

[Jay Bee]

Picture is of a 318 version.

The link is some info on the 3 nipple ones.

https://www.forebodiesonly.com/forum/threads/3-port-valve-cover-breather-1970-1971-engines.17111/

[70/6chall]

Here's some information on that valve cover hole. Thanks,   Al

[70/6chall]

Sorry here is the information, hit post to quickly, duh.   Al

[tman]

Needs something like one these in the photo.  If you are going to use a stock air cleaner then the single nipple should work.  This one shows 3 nipple and there are 2 nipple also. 

https://vansauto.com/product/mopar-1970-1976-paintable-valve-cover-breather-3-nipple/

https://www.forabodiesonly.com/mopar/threads/1970-up-valve-cover-breathers-1-nipple-2-nipples-3-nipples.442434/