ARB is the only manufacturer I know of, but I think they make "Safari Snorkles" or are associated with them.
As far as waterproofing, Painless Wiring makes waterproof connectors. Also, Eastwood catalog sells some cool "liquid" electrical tape that I think would be fairly waterproof.
You can use some di-electric grease around the lip of your dist. cap to assist with water proofing, as well as spray some silicone spray around the outside of your plug boots.