What stereo will fit into the rather large stereo whole that the old one with a cassette wil leave (due to the err message)
Due I need a special fitting tp put a newr one in?
It's a standard double DIN size. You can either fit a double DIN unit, or get a 1DIN and fill in the space with a 1DIN blank, or a cubby hole or clock or similar. Lots of people make stuff to go in the gap left, including mx5parts.co.uk
By fitting a single DIN unit and a cubby box you have a great place to keep your shades.