Curiously I HAVE tried the largest real plumbing supply shop I can find in
the North East called New York Replacement Parts Corp at Lexington and 94th
St in Manhattan. They at first told me that they couldn't identify it from
the old one or the spline look and asked me to get the old one out of the
wall and bring it in to show them. Then they deny vehemently having anything
whatsoever for a US Brass Valley Line Old Style and then told me to go to
any hardware store for a fitall one.

My local Home Depot was where I then found the useless Danco and then some
other place the $7 thirties-retro ones I am using while I try to find a
proper replacement which isn't too hideous.

Does no one on-line carry a selection of this sort of thing?

Have you tried a real plumbing supply shop?