99-00 have a chrome housing and clear lense...01-04 have black housings with a smoked lense.  Get the 01+ ones.  the smoked are always better.  other than visual differences between the 2 year ranges, they are identicle.

and please...PLEASE make sure you get OEM lights.  NO aftermarket, they will leak, fog and fit POORLY.  I may be able to get you a good deal on the lights.

these are the ones i bought.  They are OEM lights.  HERE

I checked my hookup at the ford dealer and the best they can do is around $190 for the pair.  so that ebay deal is pretty good.  be careful of anything cheaper. 

i have the dark ones they are awesome try to get the ford ones  had after market and when it rained the lens foged up inside not a good thing goodluck

Luis