I just wanted to clarify the differences in bones:
Beef bones are not all going to be okay, because there are many different types of bones in an entire cow. There are also many types of marrow bones - in fact, almost every bone has marrow in it. With that said, however, most "marrow bones" that you find at your butcher shop will likely be femur bones. Also, there is only one type of femur bone
, and they are found in the hind legs. The bones in the front legs are called the radius and ulna.
I'm glad I found this thread!
I've called one store and they said they did not have them. I'll have to call around some more.