Here is a link that Brian posted on the Holley Retrobright LED, 4X6" headlamps.
http://www.transamcountry.com/community/index.php?topic=84792.0The Holley LED are a great upgrade to the OEM 4X6" bulbs that came in 1977 -1981 Firebirds. At $180.00 per bulbs they are expensive. When Brian brought to my attention a sale at $80.00 per bulb, I purchased two low beams. I am very happy with the performance and like how they have retained the original look of lamps from that period.
A couple of weeks ago I attended a car show about an hour from my house. My route home took me down very dark rural back roads. I still had the original factory high beams, one which was burned out. This left me wanting for something better. I found these Phillips H46151CV lamps from Rock Auto for $13.07 per bulb. I ordered using the cheapest shipping $8.99 and they arrived the next day.
IMG_4109 by
Lawrence Alexander, on Flickr
The Phillips bulb is glass and looks very similar to the OEM bulbs.
IMG_4129 by
Lawrence Alexander, on Flickr
Daytime photo with Holley bulbs installed (two outboard lamps). Passenger inboard lamp (left on photo) is Phillips H4651CV. Drivers inboard lamp (right on photo) is OEM bulb.
IMG_4105 by
Lawrence Alexander, on Flickr
Both Phillips high beam (inboard) lights installed. As soon as I get a chance to drive on a dark country road I will report back on real world impressions. At this point I am pleased and feel these bulbs are a good value.
I do feel the Holley lamps are still brighter than the Phillips. It's easier to notice in the upper photo showing more of the bird decal looking at the bulbs at an angle rather than head on.
IMG_4134 by
Lawrence Alexander, on Flickr
IMG_4136 by
Lawrence Alexander, on Flickr