Hi Tom,
I have the Yashica Mat 124G and it uses both 120 and 220 film. There are older models. The Yashica Mat 124 also uses both 120 and 220 film.

There are also Yashica Mat EM and LM models and I believe they only take 120 film.

Here is a link to all models: Yashica Mat Information

I hope this helps.

Regards,
John