wow! i think that might be the difference between getting a seal replaced vs. a whole new wheel motor.

i have had 2 seals done on mine it was around 3500 each if i remember... had some other things done at the same time like kingpins so cant remember exact price. 

original poster. just because your seal is leaking doesnt mean you are going to have a wheel motor go bad. i dont know exactly why those would go bad but i guess they do... a seal leak like what yours is is something i would wait to change till the whole tire looks bad. (in a days time)

one thing to help keep your wheel seals is every day before you run, grease the wheel motors. there are 2 grease zerks one on top and one on the bottom of the wheel motor. maybe 3 shots of grease for each. doesnt take much. but that grease keeps dirt out of the crack. it seemed to me that if i greased them too much then they leaked worse? just a couple shots per zerk every day is what ag chem suggests.