Ghost, close as I could come was 1926-7 Cad and 1926-28 Lasalle. But it looks like they used 10 1/8" Monograms.
Here are some I found on E-bay for a 30-31 Lasalle, but he doesn't give size. Others were marked 30-31 Reo that were 10".
Closer/clear pic of lens/bucket with dimentions (lens size 10"?, bucket, ring, depth etc) and lens/bucket markings might help too.