CD changer (99) A4 avant

[Quickoldfart]

Hi all.
I have just bought a (99) A4 avant which has the concert stereo, I want to fit a CD changer (as there are several on ebay) & would appreciate any advice.
I believe my car has the wiring & connector fitted as standard, where on the car would I find it?
Will any Audi/VW unit be compatable? will I need any pin numbers or codes?

many thanks

QOF

[Quickoldfart]

Well after a bit of digging I found where it goes, but couldnt see a connector cable. hmmmmm!!

QOF