The Speedway listing for the parts says "2 per car", which was confusing.
https://www.speedwaymotors.com/OER-K687-Window-Guides-1968-69-Camaro-1968-Firebird,275326.html?sku=92632963&utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gclid=EAIaIQobChMIztDAocrG9QIVGx6tBh0DsQHvEAYYASABEgJg7fD_BwE