iv got the standard screen( time, date,temp) in my car and want the trip comp type.

what will i need to fit the trip computer to it?

iv had a good read on here but come up with four or five different answers on plugs and so on, so can anyone tell me exactly what i need to sort mine out.

im pretty good with cars but never had a vectra c before so im just finding my way around its good and bad points lol.