LENCO CUPRONICKEL TUBE OIL COOLER, A=6", Bib Diameter 1-1/4" - Transmission and engine coolers. Replacement transmission oil coolers for use with all transmission models used with gas or diesel marine engines. These coolers may also be used as engine oil coolers. Each cooler is constructed entirely of cupronickel with brass fittings and is designed to stand up to the most rugged marine applications. The coolers are available with popular hose size bibs and 3/8" N.P.T. oil connections.