After an 8 month wait I just picked up my Guide Lamp M3A1. I'm thrilled to finally get it! The Form-3 showed "US" as the manufacturer and the BATF didn't like that. They sent the form back and wanted that updated with more correct information. So the Form-4 now reads Guide Lamp Div, General Motors Corp, USA. Fortunately they did this without completely starting over, so basically I was able to keep my place in line.
Anyway, happy to finally have it! The first thing I did with it was change it over to the M3 guide rod assembly with the large backplate.
Here it is.