OK, perhaps pictures will help????
^^^Notice the difference between these bulbs. The beige colored one is an 894 and the black one is the 898 in the 04+, nonGXP Grand Prix's. The difference? Just the round, rubber gasket that the 894 has, that's it. The wattage is the same and so are the grooves that lock it into place.
^^^Notice the back of the foglamp and how it has rubber material around the slots that lock in the bulb. This is why anything other than an 898 won't fit this housing...unless you remove the rubber gasket on the bulb itself. If you remove the gasket from an 880, 893, 894, 895, etc. it will fit.
^^^ The HID bulb in the foglight housing is an 880 that has had it's rubber gasket removed.
^^^880 HID bulb without the gasket.
^^^The front of the 04+ nonGXP foglight/turnsignal. The top half is the turnsignal and the bottom is the foglight with the 880 HID bulb installed.
I hope this helps.
