What kind of headlights fit a 67 firebird without
modifying the opening? The halo/halogens look cool.

Take a look at these. They have a very good product and stand behind them, unlike a lot of the flea bay dealers! [http://haloheadlights.co/]LINK[/url]

Most of the aftermarket modern lights I have seen require you to hack up the factory wiring harness.

RedLine LumTronix doesn't make you hack the wiring up, they provide you with adapter plugs that are ceramic that you plug into your existing wiring and into the headlights. Best of all, each is American made and each one is made individually.

When I changed the Bird's lights for driving on the left I replaced the old Wagner sealed beams to H1 and H4 units.

The adapters above are very close to what I made for the H4 Low/High (outer) lamps.

The H1 High beam (inner) adapters have a 2 pin plug at the harness end, with two 'flying' sockets at the lamp end, one to the H1 bulb and one to the ground terminal on the lamp reflector.

All parts are low cost and readily available on ePay... but of varying quality. I ended up buying enough for a few adapters and picking the best to use on the car.

If you upgrade to halogens, make sure you use the adapters for the wiring with the ceramic connectors. The standard connector will fit the H4 bulb, but it will be way too hot and you will damage your connector/wiring.

As others have mentioned, I upgraded to the H4/H1 set up, but I also added a relay kit to help eliminate the voltage drop to the lights. The drop in light output (lumens) is exponential with the drop in voltage. A relay kit insures you have full voltage at the lights. The stock set up has the power basically running from the junction post (battery/alternator power) through small wires into the headlight switch, then back to the lights. That's very inefficient. With a relay kit, the power goes right from the junction post to the lights. The switch just activates the coil on the relay.

I have a post somewhere on this when I did my conversion a few years ago. I went with the clear beams with the facets in the reflector behind the bulb for a more modern look, but there are plenty of housings out there with the facets in the lens to look like a stock sealed beam.

I am very happy with these: http://1967firebird.atwebpages.com/body5.php

I also put relays in for the high and low beams.

I also put in relays for the headlights, I was getting below 10 volts to the lights and now get 14.2 while driving. The difference in the amount of light is amazing, no need to spend bucks on upgrades and the lights look stock, not like they came out of a VW.