[aphaynes]

Originally Posted by lizziemeister'sV6

There is 1 PVC valve threaded into each head under the valve cover - not 2 in each head as posted in the proceeding post - in 1966 and earlier V6's - behind the left valve cover in the block itself is a filter can pressed into the block with a screwed on lid that houses a paper element. Both PVC valves and paper element can be purchased at reliable parts stores.

I got the paper element referred to above at Napa.
Item: Crankcase Ventilation Filter (Gold)
Product Number: FIL 2718

I am sure I also got the two PCV valves as well, but don't recall the part number. However, there are part numbers on the site here: http://6066gmcguy.com/partnumbers.html