Ive looked at the PDF on this site but its dated 2002.... is there a more current manual for removing the HU/installing aftermarket?

Pop off the U shaped bezel surrounding the HU. Just use something thin to slide between the cracks and pry it off. There are 4 screws holding the mounting brackets to the dash. After that, pull out the HU and remove the clips from the back. Done.

Everything should be clear and straightforward regarding installing a new HU.