Bones that are okay for dogs?

Here's the dilemma. I want to feed my 75 lb doberman bones to clean his teeth. I am not talking about the rawhides or the garbage bones they sell at Petsmart. Everyone tells me beef knuckle bones are good for dogs. Problem is, I can't find them. All the grocery stores tell me they never get them, and I have no local butcher shops. So I tried feeding my dog cut up marrow bones. The problem is that because of the shape of the bones, he never uses his back teeth to get the marrow, so it is kinda useless for teeth cleaning. I bought other bones but he just chews them up and swallows them. I was thinking of getting beef or pork rib bones but people tell me those are major choking hazards for my dog. So what is a COMMON BONE that I can find in a LOCAL GROCERY STORE that will be okay for him? I know no bone is 100% safe, but some are definitely better for cleaning his teeth than others.