If the front end of the horn is rectangular, approx 4" x 8", with a square back end, it is by Hadley. The logo is on a rectangle that occupies about 2" x 4" centred on the cover plate.
If the front end of the horn is rectangular, approx 3" x 6", with a round back end, it is by Fiamm. The logo is a "peel and stick" beaver, stuck to the cover plate.
Most older Beavers have Fiamm horns, to at least 2003. I have only seen one newer (2005 to 2008) with Hadley. This in a park with 18 different Beavers, where we stayed for the past month.
I replaced my Fiamms with Hadley to get more volume. I too would like to have new beaver logos, so if you find a source, please post it.