Wingin: Here's a thread I submitted a while back when I converted my GL1500 to LED. A lucky conversion, I might add, since my alternator died coming back from Alaska and I was saved by Hanko and his bevvy of spare batteries.
With a bit more work you can replace the bulbs with LED strips and get a lot more light. Purchase the LED strips from http://www.meritline.com/waterproof-led-strips-red-16-feet---p-72360.aspx The strips are waterproof and self adhesive and can be cut to size. here are a couple pictures to show the difference. To replace the bulbs, you have to pry apart the lens from the base, use a heat gun/hairdryer and be careful. Also be sure to use RED LED's behind the red lense...if you use white LED's it will appear pink. Same with the amber!
+1 on the LEDs I did the conversion on mine . Got the strips off ebay very cheap and after a little modding of the stock lens they were in .
On top is the strips and underneath is the bulbs they replaced