I think I may have found a suitable shaft that already has a keyway cut along the entire shaft. Do you all think a 0.125 deep x 0.250 wide slot is suitable? The slot is the correct depth/width for the sliding yoke side, but it is cut shallower on the fixed end yoke side where the woodruff key would have been employed. The woodruff key is 0.375 high so the slot on the shaft would originally have been 0.250 deep on that end. Do you think a length of 0.250x0.250 key welded in the shaft will be suitable on that end?
Thanks for the Spicer/Dana link Grigg as it produced a viable (although obsolete) part number. The vendor was surprised to see interest in a part that has languished in a corner for decades. If it works, this alternative will be much less expensive than the other alternatives. I still have not purchased the shaft as the young guy on the phone wanted me to wait until the "old guy" at the parts desk came back to work as he "remembers when this old stuff was actually used".
Stovebolt rocks!, thanks for the great intel.