AK Fans: Will this Speaker Work with My Receiver?

[Winky Dink]

I have an AK model 37 with its original cone speaker. It looks to be in good condition, but I haven't touched it yet.
Someone is selling a horn speaker, model M. I think that Atwater Kent, in 1927, was offering both the horn and their new cone speaker for the same receivers.

Does anyone know definitively that the Model M speaker will (or should) work with the Model 37 receiver?

Thanks,
Winky