Thanks PRR. I was relying on my memory for the location of Volcano, but like you, I definitely located the wye location on TerraServe. It clearly stands out on the photo. The location should be easily found on the ground. I haven't stopped long enough to look for it, but it doesn't appear to be more than a few hundred yards west of US285. I can't tell you the mile marker, but it is in the vicintity of the left hand curve (going south) at the end of the long relatively straight stretch along San Antonio Mt. stretch.