just wanting to know how is it done and if anyone has diagrams would be helpfull i got a vx ss
Usually, the dash will need to be dismantled and the unit screwed in from the side of the chassis that holds the original unit. IT won't be the same size as the stock head unit so you'll need a surround/trim panel to cover any gaps around the edges.
Here are some instructions on how to dismantle the dash: instrument_full.pdf