While going through RockAuto for a 240 water pump, did the usual scan to see what other items would be worth adding to the order from that shipping location. Looked up spark plug wires in the ignition section to find one of the entries has a core charge assigned to it. https://www.rockauto.com/en/catalog/volvo,1991,240,2.3l+l4,1287053,ignition,spark+plug+wire,7224