Here is the copy of the Army Manual for the Greaves 2xs and 2h mills.
http://www.metalworking.com/DropBox/_2001_retired_files/greavesmill.pdf It is too large to upload here for posterity so I am putting a link instead. If the link goes bad pm me and I'll email you a copy.
I just picked up a Greaves as well that also has the toolmaker's overarm. I don't think they are common but if several are trading hands at one time maybe they aren't that rare either. Mine is also a universal mill with swivel table. I can't tell by looking at the pix if yours is a universal mill or not? The overarm and swivel combination sort of grabbed me. 7.5hp on the horizontal and 3hp on the overarm and 50 Tapers makes for a pretty neat package.
I am interested in an owner's manual, parts book, etc--I usually try to buy an original copy but would be glad to get my hands on a copy of Greaves material if someone has anything.