The specs for the gearbox are: Size: 67.7/Ratio: 20:1/It Measures: Input Shaft: 1.0" Dia x 9-1/4" Long with 1/4" KW the entire shaft length Out put shaft: 1-1/8" Dia x 15-3/4" Long with a 1/4" kw x 3" long starting at the housing and another 1/4" x 3" keyway starting 1-3/4" from end of shaft