The washer is not keyed. My only concern is after I preloaded the bearings and spun the hub several times I backed it off to where I could get the cotter pin in. The nut is loose enough that I can slightly turn it with my fingers due to the difference in size between the cotter pin and castles.
Here is a parts diagram:
http://www.lci1.com/assets/content/support/complists/5200-Spring.pdf
This is not my first time packing bearings. I did it several times in my old trailer and grew up doing it with my dad. I guess I am just paranoid now after reading so many cases of bearing failure!