Sierra 18-1936 Riser The Sierra 18-1936 Riser is interchangeable with the following: GLM 51520, Volvo Penta 857037. Each Sierra product meets or exceeds the original equipment part it replaces. Sierra Riser Meets or exceeds the original equipment quality Sierra part number: 18-1936 Interchangeable with the following: GLM 51520, Volvo Penta 857037