This is a very nice pair of 1970-1974 Pontiac exhaust manifolds for 350 400 and 455 engines.  Manifolds are in very good condition with no cracks or other damage. GM casting numbers 490143 date l123 LH side has flange still installed studs may be ok, not sure. 490142 RH date E084 has good usable studs. Great for any Firebird GTO LEMANS or Grand Prix restorations. Tough to find a pair in this condition. These manifold have the 6 bolt holes to the heads for much better sealing than the 5 bolts. Best fit quality and appearance with Genuine GM parts.