Hasselblad 40mm C T* Filters?

I am sure this has been answered already, but I have done a lot of digging trying to find out what my filter options for the older style c lenses are as far as filters are concerned. I keep coming across claims that the bayonet 104 fitting is the same as the bayonet series viii(8). I then can find other sites that state that in fact the series viii filters are quite a bit smaller.
Are bayonet 104 filters equal in size to the bayonet series viii filters?
If not, are there bayonet 104 filter equivalents?

The Distagon 40 mm lens takes filters 104 mm in baynet mount. These filters are quite difficult to obtain.
Hasselblad swa, swc and distagon c 50 and 60 take series filters ser. viii = hbl ser 63.
Carl