Yes you can. They are still the same bobbins even if they look slighly different. I think the old Singer machines originally came with 6 bobbins, that's what both my 99 and 201 came with. The problem I have had with brand new metal 66 bobbins is they act up with the bobbin winder. They are very nice and polished on the outside, but inside the "hub" they aren't always that polished; which means they don't always go on the bobbin winder. It's not a big problem, but to give you an idea; I bought 12 bobbins on e'bay, and I think I threw 6 of them out. They all worked fine in the bobbin case, maybe I could get them on the bobbin winder with a bit of wiggling and force, but I just could not live with that. Some sellers are aware of this and test their bobbins, but I have heard some complaints even from most reputable sellers.
The plastic bobbins work too, they are often called Apollo, or just class 66. Some find their machines behave better with the metal bobbins, but I don't notice much difference. I prefer metal bobbins, they look right the machine and last forever.