If you are speaking about the engine crankshaft pulley to pump shaft and connecting hardware/coupler, its been discussed here. I have to believe its a common part, but in a quick search was not able to find a shaft, but I did find what I believe to be the front coupler off the crankshaft pulley. Going from memory on mine, you have that, the shaft that passes through the front axle pivot pin to another flange or coupler with 4 bolts, then to the pump input shaft. Once apart you should be able to determine what was damaged. When that pivot pin is worn and has excessive play, when using the loader to raise the front end, it will rub, mine does on an 850, and its quite worn. I looked at Lovejoy, and Surplus center websites, briefly, did not find a shaft or anything related, but wait for others to comment, someone will know a bit more, and more research might turn something up, drawing a blank on where to source that splined shaft.