I can't help you with the identification of your helmet but I can say that you probably won't have any trouble selling it on eBay.
When I had a clear out of my old ex-military flying gear (cloth inner helmets with electrics, bone-domes, H-type oxy masks etc) a few years ago I was astonished at the prices people were prepared to pay - veritable bidding wars, especially for the H-types! My old (and exceedingly battered) SD hats also found ready buyers but that's another story.