72 GMC single lamp dual beam headlights

[Stocker]

Looking at that link, it appears to be a sealed-beam lamp. Not what I had in mind (sorry) -- I didn't think Hella even made those....

That site does carry E-code lamps, though, and that's what I would choose over sealed-beam any day.
This looks like the right ones: http://www.rallylights.com/detail.aspx?ID=733 I have not found a need for higher-wattage (and more costly) bulbs. The 5006A - 60/55W Hella bulbs (H4) work very well.

You could call 'em for more info.... I've dealt with them before, they're very helpful.

If you want a true bi-xenon HID, I think you'll end up paying quite a bit more. That's something I've never really looked into, though.