Ulf,
The aBay parts SimS has you looking at could work, however I'm not sure the ratio percentage is the same from the 40's to your '58...you would need to comfirm that.
If your looking for another adaptor I think I have one with a bad diaphram. It could be made to work manually like the one on eBay. I've never been able to find replacement diaphrams, and all of the used adaptors I've found the diaphrams are bad...
Mike B
