Rarely is shipping "free", especially when you're dealing with truck-freight.. They're just building the shipping-cost into the price of the parts, and assuming/hoping you won't notice. This "grift" has gone viral in mail-order marketing over the past couple years.
What I see on their site are quarter panels of likely Taiwanese origin (Golden Legion or Golden Trust). They're charging $159.95 per side. So you're looking at roughly $320.00 for the pair, delivered, and they say they won't even ship until a week from today (which means they aren't stocking the merchandise).
Comparably, we sell Golden Legion 65-66 coupe quarters for $109.95 per side, and charge $120 for truck-freight to Indiana. So roughly $340.00 for the pair, delivered, and you know the actual manufacturer of the quarter, and you're not waiting an additional week for them, and if you've got problems, you're not triangulated between a large vendor (Jegs) and a drop-ship-distributor (Sherman). And if you needed any additional parts, they could all be packed-in with the quarters so they'd ride for free, which truly IS the essence of "free shipping".
Anyhow, point being, the shipping isn't free. It's just front-loaded. Don't let marketing-schemes fool you.