I usually get ferrites and iron cores from CWS Bytemark. Newark carries some interesting ones, although they are not my first go-to. I have also gotten a few from Amidon.
I don't think the key was beads-on-coax, but more the material and the amount of material. There is about a foot and half of beads on the choke right at the radio connector, it's really sorta awkward since my radio is under the passenger seat and the coax is poking out like a tentacle. :-)
I do plan on re-turning the choke using known material toroids or maybe binocular cores and putting one on each connector (probably mix 67 for the VHF) and one at each end of the HF feedline. Putting the choke in or wrapping it with something to protect it from getting broken.
Common coax cable type outer diameters.
RG-58 is 0.195"
RG-8X is 0.242"
RG-8 is 0.405"