[big gear head]

Before going any farther go ahead and take the rest of the gears out and see what the case looks like inside. I could be wrong about the wear on the case, and if I am then the fix is easy. It looks like one of those thrust washers has been replaced at one time with one from a Eaton Posi, which is why it fell out. When you get the axle gears out look at them and see if they are worn or turning blue. Also look in the case at the area behind all 4 thrust washers and see if it's worn. If your case is good then I probably have a set of gears.