Hmm, thanks for the reply but totally off point lol (no offence)
There's a bit right at the back that sticks out - in the standard stereo it had a bung in the back which slotted in nicely to this bit, however my new one doesn't have a bung lol
But now anyways another problem has arisen!

My CD player just turns off, and doesn't turn on unless I have the key in a certain position in the ignition... any ideas guys?
All help appreciated (thanks again Bazzer)