Thanks guys, pretty sure this bike is all aluminum except for the fork. I know they made some with carbon stays around the same time that had problems with separating from the aluminum but i just went and tapped the stays with a knife and they sure sound like aluminum. I also included a pic of where the stays attach to the drops and it looks like a weld to me. There's also a pic that shows the 63S stamp on the bottom bracket. Since none of my own measurements really match up perfectlyl to what the Bianchi specs are I'm wondering if that means this is a 63cm size. I thought it was a 61 from measuring the top and seat tubes. Wheelbase came out closer to the 63 size.

The webpage has been updated with slightly better pics and the cracks are highlighted now.

Al1943's question about torquing it while watching the cracks was a good idea and yes, I can definitely see the cracks open up on the worse side. Looks like the chainstays are barely hanging on by a thread. Maybe even something other than the metal. Maybe paint or coating? The inside foam? Must be pretty hard foam.

great forum here, all these responses so fast. thanks.