Mckay Marine sells Cummins engines and parts specialize in Marine. Mckay Marine sells 4B 3.9 long blocks, 6B 5.9 long blocks and 6C 8.3 long blocks. The long blocks fit Marine, Industrial, Truck and Gen-spec applications. Also sell complete Cummins cylinder heads, marine exhaust manifolds and NT855, K19 marine replacement parts.