Pulled off my front driver drum today and the new shoes were somewhat wet and had asbestos mucked up a bit in the holes where the shoes are rivited.

I put in new wheel cylinders about a year ago (E350 Ford ones) and am assuming its the front seal for the axle, although I am not sure. I was able to use a can of Brakekleen and a toothbrush to clean the shoes off rather easily.

Any ideas? How hard is it to replace the front seal - any pictures? I do have the manual, just not in front of me now. I cannot imagine the wheel cylinder leaking since they can't have but 100 miles on them. I am assuming that the knuckle/axle seal may be original...and 40 years old.

Any way to tell what it is?