Nate
Yes the Koenigs adapter does work with the Becker Mexico. The Koenigs adapter is available in mono and stereo versions. I required the mono version for my late 1960s Becker Mexico which I had always thought was a stereo unit.
The man at Koenigs is very helpful and if you e-mail him a picture of the DIN socket at the back of your unit, he will identify the adapter cable which you want.
Regards
Andrew