Hi Farrell:
What is for sale on eBay is a Merrill Engineering Company Model 29A Ignition Suppression Kit apparently made for the U.S. Navy to suppress the ignition system on
any late war 1/4-ton 4x4 jeep, presumably when used near aircraft or an airfield. The Merrill kit parts that surround the distributor are designed
only for the late war Autolite model IAD-4008 dust proof distributor, and do not fit any other jeep distributor. The kit for sale was shipped in 1955 from a Naval Air Station in (presumably) Northern Virginia, and is one of 35 such kits shipped at that time. It is not necessarily waterproof, although it appears very similar.
I'm not sure when it was made, but the Model 29A kit is designed primarily to envelop and suppress standard only the late war MB (GPW??) ignition system parts on jeeps having the IAD-4008 dust proof distributor. So the kit could have been made for the Navy (or Marine Corps) during WW II or sometimes after WW II when the MB and GPW were still in widespread use. No date is found in the Manual accompanying this Merrill kit. In any event, it is not the waterproof ignition system installed by Willys-Overland on the MB-NB at the factory.
The correct factory installed waterproof Deep Water Fording ignition system for the MB-Navy Basic was made by The Electric Autolite Company in Toledo, Ohio. Its various components are discussed, identified and pictured in Lloyd White's
The Evolution of the Willys-Overland MB Jeep, Volume 2, Chapter 16, from pages 537 to 554. Although some parts are common, such as the C-10-S spark plugs, the Autolite waterproof components are in fact different, and are even more rare than the few found Model 29A kits. Nevertheless, the kit on eBay would be a decent appearing substitute or placeholder until a person tracked down all the correct 1945 waterproof Autolite ignition system parts, a very arduous and challenging task.