Best way to get a flip top gas cap on a dart

RANI just buy this http://www.ebay.com/itm/1968-Charger-Barracuda-NOS-MoPar-Flip-Top-GAS-CAP-4Lock-/140436893875?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3ABarracuda&hash=item20b2b0f0b3&vxp=mtr