Standard rubber O-rings. The small one on the axle nut is 1/8" x 1-3/8"OD and the big one on the hub is 3/16" x 1-7/8" OD. There is no seal inside the hub, but the hub seal that goes inside the knuckle housing is a Nationa 473455 for the steer axle and a National 715100 for the non-steer axle.
I sell a package that has the small O-ring, the large O-ring and the axle nut retaining roll pin for $4 per wheel + Shipping, runs about $19 total for a set of 4, PM me if you are interested.

Chuck W.