Beginner's guide to 550/575 headlights

Could someone kindly demystify this particular topic for me. Have done an extensive search but it has left me a little confused. A while back I asked on the technical forum how to dismantle the headlights and paint the coloured surface inside, and the gentleman from Harmony Autosport was extremely helpful:

http://www.ferrarichat.com/forum/showthread.php?t=134264

Unfortunately his solution of heating the headlights in an oven in order to prise the lens off has not worked on mine (the car is now ten years old in a very hot climate, and perhaps the glue is just too hard now).

I guess this means I am just going to have to bite the bullet and purchase new units. Would really appreciate some help as follows:

1. Is there really no way of purchasing just the plastic lens (i.e. I would break the existing lens open, paint the surface, then just glue on a new lens)? The Eurospares website does not show this lens as a separately available part.
2. My current headlights appear to have xenon bulbs but no control unit. If I choose to upgrade to complete 575 lights, do they fit and what difference do these make? Are they more expensive than 550 lights?
3. What are the chances of finding second hand headlights in the UK or US (rosso corsa)?
4. If second hand is not an option, where in the UK or US am I likely to get the best deal?

Many thanks in advance!

Harris

 

Thanks Desmo.

Anyone have any idea what differences there are between 550 and 575 lights?