I replaced my 2001 f150 headlight assemblies with a pair I bought on ebay
that included projector driving/fog lights.  I use a street legal bulb - I
think it's a sylvania silverstar
http://www.sylvania.com/AboutUs/PressAndNews/PressAndVideoReleases/SaferRoadTrips.htm

I don't think I bought from this seller, but the link gives you an idea what
is out there.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7966951906&ca
tegory=33710

I also bought a ford healight adjusting tool on ebay - not cheap, but it
makes headlight aiming so much easier.  it has a self contained ratchet to
fit the tiny stub on the adjusters.

note: I did have to notch the headlight mounting area to accomodate the
larger reflector in the front end of my truck, but it was worth it.

Try the following product. It may be cheaper then trying to find new
lenses. http://www.properautocare.com/plaslenclean.html

Bruce

MacGuiar's Plastic Polish will do the trick with some elbow grease and
a soft rag...  I've got to polish' the wife's Cherokee headlamps a
couple times a year 'cuz they scratch like crazy.  (POS Chrylser
product...)