[Captain Planet]

I cleaned my antilock sensors on the front of my 2000 Surburban and when I cleaned the passenger side the o-ring fell apart. I called my local dealer on the part, but Chevrolet doesn't list it!? I am currently waiting to hear back from them to see if they can at least get me the dimensions of the o-ring so I can get it somewhere else. Does anybody have any idea what size this o-ring is?

Thanks,