Problem: want to play CD's & cassettes in a Contour
Solution: aftermaket tape deck CD/ changer controller and CD changer for the trunk
The Contour OEM system sucks. Complicate it with the external amp the CD HU requires and it is just going to end up costing you quite a bit to get it to work, and then you have to use the u-tool to swap every time. What a PITA. I had a Sony tape deck in my SVT with CD changer control and a 10 disc changer in my trunk. The HU (refurb) cost $140 and the same for the changer. I sold my OEM CD head unit on eBay for $202. Sell both of your head units on eBay and you will probably come out even on cost, and you'll have much improved sound when you bypass that factory amp.
Just some ramblings...
Aaron