They are different part numbers....
The part number he has is 15220039 (left) 15220040 (right).
My 2001 headlamp part number is 25718687 (for the left, and ends in '6' for the right).
I saw an older lady driving around in a GXP with the darker headlights. I would say those are stock for '05'*. I doubt the lady I saw would smoke them herself.
Originally Posted by eBay Seller
These smoked headlights were standard equipment on the Pontiac Bonneville models SLE and GXP in 2005.
I'm guessing that'* accurate...?
EDIT: Also check out DBnewfie'* '05 GXP - his are darker...