Thermostat Housing Bolt Kit, 12-Point Head Black Oxide AR134-7401Thermostat Housing Bolt Kit, 12 Point Head Black Oxidefits GM LS Series 20mm UHL AR134 7401 134 7401 THERMOSTAT HOUSING BOLTS Nobody likes water leaks. And here's ARP's contribution to the solution. These premium grade bolts are engineered to properly engage the manifold threads and resist loosening. They're application specific, and come in your choice of black oxide finished chrome moly or rust proof stainless steel, with handy 12 point or standard