U r right DOC, except the Allen-Morrison was located in Lynchburg, VA. The Co. is no longer around and the AM code on your signs mean batch numbers.
I to looked up the Co. on the web tjccafferty, and very little came up. I live in that town of Lynchburg and remember the Co.
Sometime the sign will have Lynchburg,Va stamped on it also. Th Co. produced approx 80% of the signs country wide, then china came into the picture.
Im not sure when the Co. closed but I do remember the building being torn down in the late 70s.
Hope this helps!
HAGD,
mike