This is the main shaft of waterloo built number series two cylinder tractors for the power steering pump. Fits JD models 50-730. The 80/820/830 use a different shaft. Our shaft is precisely made here in the USA. It is a case hardened steel shaft, precision ground, with minimal run out. The key provided is alloy steel and the shaft is provided with two key cuts. The spline count is ten with a major shaft dia. of .745". OD for gear and seal surface is 1.000". We also have the complimentary shaft GP- F1685R, coupling shafts, splined couplers, bearings, etc for a more complete one stop, one shop for these hard to find parts.