Phil:
You might try looking on the transformers, coils, chokes, yoke, etc. for the EIA codes of the makers of the components. That may give some clue as to the maker. For more on EIA codes, you can go here:
http://www.triodeel.com/eiacode.htm
There is more complete mfg code info here under RMA List:
http://www.oldradioz.com/id99.htm
Is it a 12" or 16" CRT?