The S&W dual exhaust manifolds will fit B and C body cars from 1965-1970: Starfire, Delta, Dynamic 88 & 98. They have GM casting numbers and will fit 400, 425 and 455 Oldsmobile engines. The S manifold is special to the 1965-1970 Starfire, Delta & Dynamic 88 and 98 because of the rear mounted steering box. The W manifold (passenger side) is from the 1965-1967 442 and will replace the passenger side to fit and function without the crossover pipe. Both manifolds are available to purchase separately as well.