CODE for Ford 1996 MODEL,RDS Radio 6000CD?

Hi can you or ANYONE help me get my stereo/radio code as i changed my Wife's Battery in her car and when i went to put the stereo on it asked for a code only to realise we were sold it without the code along with the manual...Dohhhh

She has been without sound for 2 weeks and dont like having no stereo and is driving me mad my serial * is M157939 i think. and the model is 1996 M-reg

Many thanks for your time signed Moses