Hi Tom,
Attached photos of the info on the valve after I chalked it up:
Donaldson Crankcase Ventilator
Take apart every 250 hrs or 10,000 miles
Wash in varnish (remover?)
Install arrow up
Donaldson (Mfg?)
St Paul (MN?)
Made in USA
US, Can, Br patents
Part No. V4 15
As an aside, Williamsburg...