looking to buy new stock springs for my 65 442 convertible, are the rear springs for the convertible different than those of a hardtop? i am seeing different parts and prices. the rear springs from oldsparts.com say for a convertible, and are twice the price of the rear springs from speedway motors. i'm not afraid to spend the money for the right parts, i just want to make sure i get the right parts the first time. i will be buying big block with ac springs for the front, i just want the correct ones for the rear. thanks for any advice and assistance