This is a 2nd Gear with 37 teeth for the 5 speed NV4500 in a Dodge or Chevrolet. You can identify this transmission in a Dodge by the cast "C-18157" or "C-23167". This transmission has an iron case with an aluminum top cover. This transmission usually comes in the 1994-ON Dodge Cummins Turbo diesel truck. You can identify this transmission in a Chevy by the cast "C-16812" or "C-18157". This transmission has an iron case with an aluminum top cover! This transmission usually comes in the 1990-95 Chevy 3/4 ton or 1 ton gas and diesel trucks.