Similar to a Brown Manly 1AA only a hair bigger. Marked A.
One sold several years ago in one of the York auctions; provenance unknown, but a tentative "Minnesota?" guess guess was included in the listing. It is roughly 6 1/2" overall length.
I've got nothing. I guess it is an orphan.
Bus.. This wrench looks exactly the same as the ACME you hsve on your sold page. Different marking. Any chance of a connection?