MPI's oil drain kit allows you to quickly & easily drain GM marine engines with a 1/2 -20 UNF thread oil pan drain plug port. MPI GM Standard Oil Drain Kit 305-0380 Inboard/Outboard oil drain kit Fits 1996 and prior GM marine engines with 1/2 -20 UNF thread oil pan drain Oil drain hose measures approximately 3/4 in. outside diameter and 42 inches long Threads into the bottom of oil pan to allow draining of engine oil Simply push the hose through the transom drain plug hole or place anywhere below oil pan Assembly includes oil resistant hose with non-corrosive brass fittings