What do you mean by number on the sticker? If you mean the serial numbers, then this is the description given at Radios and more
http://www.radiosandmore.com/ 98BB-19B132-A AM/FM Electronic Stereo Cassette with clock
98BB-19B132-B AM/FM Electronic Stereo Cassette, Low Power with clock. Works with: Premium Sound Install Kit unless Premium system already installed
It seems there's only one version of the CD player
98BB-18C815-A AM/FM Compact Disc Player with clock. Works with: Premium Sound Install Kit unless Premium system already installed.
I just recently got the CD player replaced because the dealer "unknowingly" installed a older model. So I know this is the correct number for the CD player that should be in the 1999-2000 Contours.
To guess at your question though, it seems there is a difference between the HU between premium and non-premium in terms of power, but since there's only one CD player and it would be silly to not offer a CD player for non-premium units (of course I have seen sillier things around Ford...), I would venture to guess that the HU will at least work with non-premium systems. Question is how well will it work...
