Focus Wheel Alignment...'Shims' Needed???

So, I'd like to get a four wheel alignment done on my '03 ZTW. I called a tire shop and they quoted me a price, but they said it would be more money if the car needed 'shims'. Now, the lady on the phone also said she wasn't exactly sure if a Focus uses shims. So, does anyone out there know if a ZTW requires 'shims' (whatever they are).

I called three other tire shops and they all quoted me one price; with no mention of the possibility of an extra charge if shims were required.

Whaddya' think?

Cheers!
Grug

GM uses shims on the rear, Ford doesn't