It took me some time to find them at Good Vibrations Motorsports. These type breathers show up on eBay and RacingJunk every so often but they are always $200 - $300 or more for a pair.
1972 Pro-Street 'Cuda, 500" Eagle stoker B Block, Eddy RPM heads, Victor Manifold, 850 Mighty Demon, Hemi 4 Speed, Dana 60 w/4.88 gears - Built by Hansen Racing Middlesex - NJ