Have you contacted the persons or admins at various sites devoted to hallicrafters?
This one for instance, the owner is pretty serious looks like.
Sometimes it takes a personal contact to find out such obscure info.
http://www.hallicraftercollector.com/index.htmWhat is meant is that such persons often know of other more private persons who may have boxes of old documents in their garages, and are willing to help devotees of the item in question.
That is how, after two years of searching, I found a manual for the URT-12 Coast Guard transmitter. A gentleman, a retired Coast Guard Radioman found through a network of retired CG personnel web sites, had it in his garage up on a dusty shelf in a box of old papers and stuff that surely would have been pitched out at some point. It may well have been the last surviving manual, and there are only three of those transmitters known to still exist.
A list of
h serial numbers should be easier to find!
(In a similar vein, I hope Peter Keller can some day scan and release his collection of Tektronix CRT data -for those are the finest CRTs ever made, and deserve to be used in mod scopes, should anyone wish to make one with exceptional brightness and excellent geometry.)