Farmerrik,
I would just custom make your own, using the amidon rod inside 3/8 inch PVC, (getting hard to find) or a section of 3/8 or 1/2 inch PEX "sharkbite tubing. PEX might be a bit to flexible but you could fortify with epoxy.
I obtained a Stormwise 18" using 1/2 " PVC maybe 15 years ago. I started to disect to see what type beads it contained but It was encapsulated with epoxy. I get my ferrite from Palomar Engineers,(for Ham radio baluns Material #43, but their beads might be a bit heavy). For your app, maybe Amidon #33 or Fair-Rite #31? It's hard to visually tell materials apart...Good luck!
John
