I haven't seen one of those housings for many moons. The original GM part number for the item you need is 14001967 (AC Delco P/N 15-80766). The item has been discontinued by GM. Nonetheless, armed with the OE part number, you may have luck using the parts locator network at your local Chevrolet/GMC dealer to find NOS, or to cross to an aftermarket service replacement. Try a local engine rebuilder. Otherwise, you may need to begin cruising the salvage yards.