I just had a rear, fender work light bulb fail, on a 2002 JD8410.

On the John Deere website, it mentioned an alternative was GE888 bulb. I didn't want to drive to JD, just for a bulb, drove to O'Reilly Auto, and they had similar bulbs, but not 888 series.

Found a 886 series, that had some different wattages, and manager found a 49.6 watt (I believe) and it was the largest we could find. ($11).

 I tried it, it plugged in and it worked fine.

Edit: if anyone goes this route, take in your old bulb, to compare electrical connection and the 1/4 turn twist lock mechanism (at auto parts store) make sure you look at small print for watt amount, too.

Note: Don't touch the new bulb, with your fingers, either.