Have a look at wing rigging. There can be quite a difference between flap & aileron settings between Pipers. The maintenance manual describes a rigging jig. But if you get 2 or 3 side by side and put a 1m piece of wood along the bottom of the wing touching the flap / aileron trailing edge then look at the gap between the wood and the rear part of the actual wing, you'll very quickly get an idea if one is different. There should be about 5mm gap. The better take-off cherokees might have more.