3B it sits behind the front axle nut, and provides tension on the outer race.
Its a round washer with a small 'tooth' on the inside that fits into the channel on the spindle.
In this picture it is sitting inbetween the axle nut and outter race . sorry its the only picture I had of it.


Curt Warren
Salt Lake City
1948 1.5ton Loadmaster
http://photobucket.com/48loadmaster