I always keep the old ones @swwchris but, to date, the drill holes have never been in the same places on any two cars, so I have always had to buy new ones 😂
Ha I just take plates off the new car, mark the holes on the old plates and drill new holes. To be fair if the holes never line up, in the end I will have to get some new plates due to numerous holes having to be drilled, but so far its worked well.