I think they are called Sidewinders in the US. I got them from a company here in Sweden who gets them directly from the manufacturer. There's no name on the box or on the heads.
70 W100 Power Wagon. 318 4-spd 70 Sport Fury 440 2dr HT 71 Duster 340 71 Charger Super Bee - 383/727 72 Charger "Sabotage" - 440/727 - Street/Strip 78 Warlock in beautiful patina