from what I have been told and personally researched, the 124 with 120/220 film capability and a meter is the 124G, of which I sold one this morning. I was always told that this is a 124, no meter and only 120 film capability. The 124G I sold still had a precise meter (measured against my Gossen, identical readings, and the battery is a 1.5 Mercury from my frozen stash that I use on my Nikon F's .
Was there ever a simple Yashica Mat??