Hi Bob,
I looked at the mount on google images, and it looks somewhat similar to the mount that came with my B&M.
The part number that I found on
https://www.peterwhitecycles.com/light-mounts.php is
B&M475DPB . The folks at perennial also seem to sell the same part. I wouldn't expect most manufacturers to use a standard part... [tech politics statement omitted]
If necessary, I can measure the lug depth and diameter on my light to see if it's compatible with the channel on the bottom of the beacon sinewave.
Let me know what you think.
Thanks,
Brandon